Un machin doesn't mean "a machine" (that's une machine). In fact, it doesn't mean anything specific at all. It's a filler word, used when you're speaking generally or when you can't think of the proper word for something. It's an informal alternative to une chose (a thing), roughly equivalent to "thingy" or "thingamajig," or when plural, "stuff":
C'est-à-dire... de la confiture et des machins comme ça.
That is to say... jam and stuff like that.
Caption 10, Sophie et Patrice - Le petit-déjeunerPlay Caption
D'abord, je mets un peu d'acétone
First, I apply a little bit of acetone
parce que souvent y a des étiquettes, des machins avec de la colle.
because often there are labels, stuff with glue.
Captions 58-59, Sophie et Patrice - Les lampes de SophiePlay Caption
C'est quoi ce machin-là?
What is that thing?
Je savais que ça n'allait pas être le single, le machin...
I knew that it was not going to be the single, the whatever...
Caption 110, Watt’s In - Maître Gims : J'me Tire Interview ExcluPlay Caption
Un truc is another informal way of saying une chose. It's basically synonymous with un machin:
Mais y a un truc aussi qui se faisait avant,
But there was another thing that was done before,
c'est que la police, ils intervenaient au collège...
it's that the police went in to the middle school...Play Caption
Et on va aller acheter des trucs.
And we're gonna buy some stuff.Play Caption
But unlike un machin, un truc can also mean "a trick":
Tout ça, c'est des trucs pour nous faire travailler encore plus!
All these are tricks to make us work even more!Play Caption
And there are a couple of idioms with truc that can't be replaced with machin:
Je n'aime pas faire la fête. Ce n'est pas mon truc.
I don't like partying. It's not my thing.
Chacun son truc!
To each his own!
Likewise, there's one idiom that only uses machin:
Et quand je dis un grand ancien,
And when I say a great elder,
ça veut pas dire un vieux machin, pas du tout.
that doesn't mean an old so-and-so, not at all.
Captions 55-57, Uderzo et Goscinny - 1968Play Caption
Un vieux machin is a grumpy old man, an old fogey.
You can even use machin and truc as proper nouns when you don't know or can't remember someone's name. In this case they're capitalized:
Demande à Machin* de t'aider.
Demande à Truc de t'aider.
Ask what's-his-name to help you.
*As a proper noun, Machin becomes Machine in the feminine (Demande à Machine de t'aider/Ask what's-her-name to help you). Truc doesn't change.
There's also another expression you can use when you don't know someone's name: Monsieur Untel/Madame Unetelle:
Demande à Monsieur Untel/Madame Unetelle de t'aider.
Ask Mr./Ms. so-and-so to help you.
So when you don't know the name of something or someone, or you're just talking about "stuff" in general, machin and truc are the words to use.
A direct object is a noun that receives the action of a verb, such as the word "cookie" in the sentence, "I'm eating the cookie." It generally answers the question "what?" or "whom?" ("What am I eating? The cookie.") A direct object pronoun replaces the direct object when the latter is already implied. So instead of "I'm eating the cookie," you could just say, "I'm eating it."
The French direct object pronouns are:
me (me) nous (us)
te (you) vous (you)
le (him, it) les (them, masculine and feminine)
la (her, it)
Direct object pronouns have the same function in French as they do in English, with a few important distinctions. The most notable of these is that whereas in English the direct object always comes after the verb, in French it always comes before (except in the imperative, as we discussed in a previous lesson):
Ce livre me fascine.
This book fascinates me.
Quand un copain t'appelle pour son déménagement
When a friend calls you to help him with his move
Caption 4, Oldelaf - La TristitudePlay Caption
The third-person singular direct object pronouns (le and la) have the same gender as the noun they refer to:
Le silence tue la souffrance, l'émoi
Silence kills suffering, the struggle
L'entends-tu, est-ce que tu le vois?
Do you hear it, do you see it?
Captions 21-22, Indila - S.O.S.Play Caption
La tarte à l'oignon! -Ouais, comment vous la faites? -Je la fais pas, je l'achète.
Onion tart! -Yeah, how do you make it? -I don't make it, I buy it.
Captions 18-20, Actu Vingtième - Foire aux oignonsPlay Caption
In the first example, the le of le vois refers to le silence. In the second, the la of la faites/la fais refers to la tarte à l'oignon. Both examples demonstrate another rule that applies to all singular direct object pronouns (me, te, le, and la): when the verb that comes after the pronoun begins with a vowel or silent h, the e or a of the pronoun is dropped and is replaced with an apostrophe (this is known as elision). That's why you have l'achète instead of la achète, l'entends instead of le entends, and t'appelle instead of te appelle.
Again, this only applies to singular direct object pronouns. With the plural pronouns, all you have to think about is number agreement. In the following examples, les refers to both the masculine plural ils and the feminine plural les pommes, and it doesn't change before a verb beginning with a vowel:
À l'assemblée, ils ont reçu un prix qui les touche mais les concerne peu...
At the assembly, they received a prize that touches them but concerns them little...
Caption 25, Le Journal - Nouveaux artistes pluriculturelsPlay Caption
Est-ce que tu aimes les pommes? -Non, je ne les aime pas.
Do you like apples? -No, I don't like them.
The only other tricky aspect of French direct object pronouns occurs in the past tense (passé composé). If you have a feminine singular, feminine plural, or masculine plural direct object pronoun before a verb in the passé composé, you need to make sure that the past participle agrees in number and gender with the noun you're referring to:
Je n'ai pas les jouets. Je les ai oubliés.
I don't have the toys. I forgot them.
Mais si toutes ces technologies existent depuis si longtemps, pourquoi est-ce qu'on ne les a pas utilisées?
But if all these technologies have existed for so long, why haven't we used them?Play Caption
The root (masculine singular) forms of the above past participles are oublié and utilisé. But since jouets is masculine plural, we need to add an s to oublié to make it plural (oubliés). And since technologies is feminine plural, we need to add an e to utilisé to make it feminine and an s to make it plural (utilisées).
Stay tuned for part two of this series, which will focus on indirect object pronouns. À bientôt!