Le canapé est confortable, et le chat veut y dormir.

In French, singular countable nouns usually need a determiner, such as le, la, un, or une.

• le canapé = the sofa
• un canapé = a sofa

You normally cannot say just canapé by itself in a full sentence the way English sometimes allows bare nouns in certain contexts.

Both canapé and chat are masculine singular nouns, so they take le when you mean the.

• le canapé = the sofa
• le chat = the cat

If a noun were feminine, you would use la instead.

Because confortable is an adjective, and it describes the noun canapé.

• Le canapé est confortable = The sofa is comfortable.

Confortablement is an adverb, meaning comfortably, and it would describe how someone does something.

Compare:

• Le canapé est confortable. = The sofa is comfortable.
• Le chat dort confortablement. = The cat sleeps comfortably.

In this sentence, confortable comes after est, so it is not directly before or after the noun in the same way as in English. It is part of the structure:

• subject + être + adjective

So:

• Le canapé est confortable literally follows The sofa is comfortable

This is very normal in French. Many descriptions use être + adjective.

After a conjugated verb like veut (wants), the next verb usually stays in the infinitive.

• veut = wants
• dormir = to sleep

So:

• Le chat veut dormir = The cat wants to sleep

This is similar to English:

• wants to sleep

French often uses:

• subject + vouloir + infinitive

Y is a pronoun that usually means there or in/on it, referring back to a place.

In this sentence, y refers to le canapé.

So:

• Le chat veut y dormir = The cat wants to sleep there / on it

Instead of repeating sur le canapé or dans le canapé-type place wording, French often uses y.

Because when a pronoun like y goes with an infinitive, it usually comes directly before that infinitive.

So:

• veut y dormir

not:

• veut dormir y

A helpful way to see it:

• Il veut dormir sur le canapé.
• Il veut y dormir.

The y replaces the place phrase and stays just before dormir.

Yes. That is a very natural full version.

• Le chat veut dormir sur le canapé. = The cat wants to sleep on the sofa.
• Le chat veut y dormir. = The cat wants to sleep there / on it.

The second version avoids repeating le canapé.

They are different words:

• et = and
• est = is

In your sentence:

• Le canapé est confortable = The sofa is comfortable
• et le chat veut y dormir = and the cat wants to sleep there

So the sentence uses both:

• est as the verb is
• et as the conjunction and

Yes, adjectives in French normally agree with the noun they describe in gender and number.

Here, canapé is masculine singular, and confortable is already in the masculine singular form.

In this case, the feminine form is spelled the same:

• masculine singular: confortable
• feminine singular: confortable
• masculine plural: confortables
• feminine plural: confortables

So the agreement exists, even though you do not see a visible change in the singular.

Here, y is pronounced like ee.

So:

• y dormir sounds roughly like ee dor-meer

It is a very short pronoun, but very common in French.

Yes, canapé is a standard French word for sofa or couch.

Depending on region or style, you may also hear:

• sofa in some contexts
• divan in certain expressions or styles

But canapé is the usual everyday word and is perfectly natural here.