J’ai mis une housse propre sur le fauteuil, parce que le chat aime y dormir.

Because je contracts to j’ before a vowel sound. Since ai starts with a vowel, French uses j’ai.

• je + ai → j’ai
• This is very common:
  • j’aime
  • j’habite
  • j’ai

It helps the sentence flow more naturally in speech.

J’ai mis is the passé composé, a very common French past tense used for completed actions.

It is formed with:

• a present-tense auxiliary verb: avoir → ai
• a past participle: mis from mettre

So:

• j’ai mis = I put / I put on / I placed

In this sentence, it describes a finished action: the speaker already put the clean cover on the armchair.

The infinitive is mettre, meaning to put, to place, or sometimes to put on depending on the context.

Its past participle is mis.

A few forms are:

• mettre = to put
• je mets = I put / I am putting
• j’ai mis = I put / I have put

Because with avoir, the past participle usually does not agree with the subject.

So we say:

• J’ai mis
  not
• J’ai mise

Agreement with avoir only happens in special cases, mainly when a direct object comes before the verb. That is not happening here.

Une housse is a cover—something you put over another object to protect it or keep it clean.

Depending on context, it can mean things like:

• a cover
• a slipcover
• a protective cover
• a case

Here, with fauteuil, it means a cover for the armchair.

Because in French, many adjectives come after the noun, and propre often does when it means clean.

So:

• une housse propre = a clean cover

If propre comes before the noun, it can sometimes have a different or more literary meaning depending on context, such as one’s own in some structures, but here the normal meaning is simply clean, so propre comes after housse.

Not exactly.

• un fauteuil = an armchair
• une chaise = a chair
• un canapé = a sofa/couch

A fauteuil is usually larger and more comfortable than a chaise, and it has arms.

Sur means on or onto, and here it shows where the cover was placed.

• sur le fauteuil = on the armchair

French uses sur for something positioned on top of a surface or object.

Because the sentence refers to a specific armchair, not just any armchair.

• un fauteuil = an armchair, one armchair, any armchair
• le fauteuil = the armchair, a specific one

In context, the speaker probably means a particular armchair that both speaker and listener can identify.

The comma separates the main idea from the reason that follows:

• J’ai mis une housse propre sur le fauteuil
• parce que le chat aime y dormir

In French, punctuation can be a little flexible here. The comma is often used to make the sentence easier to read, especially when the first part is fairly long.

Parce que means because and introduces a reason.

• parce que le chat aime y dormir = because the cat likes to sleep there

Compared with car:

• parce que is more common in everyday speech
• car is often a bit more formal or written

In normal conversation, parce que is usually the safer choice.

Le chat means the cat. It usually refers to a specific cat that is already known from the situation.

So this sentence suggests:

• there is a particular cat being talked about
• probably the household cat or a known cat

If you said un chat, it would sound more like a cat, not a specific one.

Here, y means there, referring to a place already mentioned.

In this sentence, y replaces sur le fauteuil.

So instead of repeating:

• le chat aime dormir sur le fauteuil

French can say:

• le chat aime y dormir

So y = there / on it / in that place, depending on the context.

Yes, y can replace more than just à phrases. It can also replace many expressions of place, such as:

• à
• dans
• sur
• chez
• and other location phrases

So:

• sur le fauteuil → y

That is why y dormir is perfectly natural here.

Because y belongs with the infinitive dormir, not with the conjugated verb aime.

French object and adverbial pronouns usually go before the infinitive when there is a conjugated verb + infinitive structure.

So:

• le chat aime y dormir = the cat likes to sleep there

Compare:

• Il veut y aller = He wants to go there
• Je vais y rester = I’m going to stay there
• Elle aime y lire = She likes reading there

This word order is very important in French.

French often uses aimer + infinitive to say that someone likes doing something.

So:

• aimer dormir = to like sleeping / to like to sleep
• le chat aime y dormir = the cat likes to sleep there

This is a very common structure:

• J’aime lire = I like reading / I like to read
• Il aime cuisiner = He likes cooking / He likes to cook

Here it means to sleep.

• dormir = to sleep
• s’endormir = to fall asleep / to go to sleep

So the idea is that the cat likes sleeping there, not specifically the moment of falling asleep.

Yes. You could say:

• J’ai mis une housse propre sur le fauteuil, parce que le chat aime dormir sur le fauteuil.

But that sounds repetitive. French prefers using y to avoid repeating the same place.

So the version with y sounds more natural:

• ...parce que le chat aime y dormir.

Not always, but very often when it means clean.

• une chemise propre = a clean shirt
• une housse propre = a clean cover

French adjective placement depends on the adjective and sometimes on the meaning. For propre, the position can matter.

For example:

• ma propre chambre = my own room
• une chambre propre = a clean room

So in this sentence, propre comes after the noun because it means clean.

Yes. In English, the best translation depends on context.

• mettre une housse sur le fauteuil can be understood as put a cover on the armchair
• in more natural English, it might also be put a cover over the armchair

So mis here is flexible: it means placing or fitting the cover onto the chair.