Mon frère veut un imperméable et un bonnet assortis, mais ma sœur préfère un gilet simple et des baskets noires.

Because French possessive adjectives agree with the noun that follows them, not with the owner.

• frère is masculine singular, so you use mon
• sœur is feminine singular, so you use ma

So:

• mon frère = my brother
• ma sœur = my sister

A useful extra point: before a feminine noun that starts with a vowel sound, French often uses mon instead of ma for pronunciation reasons, but that does not apply here.

In French, it is very normal to repeat the article before each noun in a list.

So French says:

• un imperméable et un bonnet

rather than leaving out the second un.

English sometimes allows a raincoat and hat, but French usually prefers the fuller structure with an article before both nouns.

Yes. Assortis applies to both nouns together.

So un imperméable et un bonnet assortis means that the raincoat and the hat are matching or coordinated with each other.

This is a common French pattern: one adjective can come after two nouns linked by et and describe both of them together.

Because the adjective has to agree with the nouns it describes.

Here, it describes:

• un imperméable — masculine singular
• un bonnet — masculine singular

When one adjective describes two masculine nouns joined by et, French uses the masculine plural form.

So:

• singular masculine: assorti
• plural masculine: assortis
• singular feminine: assortie
• plural feminine: assorties

That is why assortis is correct here.

Because many French adjectives normally come after the noun.

In this sentence:

• un bonnet assorti / assortis
• un gilet simple
• des baskets noires

This is especially normal for:

• adjectives of color → noires
• many descriptive adjectives like simple
• adjectives like assorti

Some common adjectives do come before the noun, but not these ones.

Because in French, shoes like baskets are very commonly referred to in the plural.

So:

• des baskets = sneakers / a pair of sneakers

This is similar to how English often talks about shoes in the plural. Even if you mean one pair, French naturally says des baskets.

Because noires has to agree with baskets.

The noun baskets is:

• feminine
• plural

So the adjective noir becomes noires.

The full set is:

• noir = masculine singular
• noire = feminine singular
• noirs = masculine plural
• noires = feminine plural

That is why French says des baskets noires.

No. Here, simple only describes gilet.

So the structure is:

• un gilet simple
• des baskets noires

In other words:

• the cardigan is simple
• the sneakers are black

French word order makes that clear because each adjective follows the noun it belongs to.

They are both in the present indicative, third person singular.

• veut comes from vouloir = to want
• préfère comes from préférer = to prefer

So:

• Mon frère veut... = My brother wants...
• ma sœur préfère... = my sister prefers...

This is the normal tense to state current wants, preferences, or general facts.

Because préférer is one of those French verbs whose accent changes in some present-tense forms.

You get:

• je préfère
• tu préfères
• il/elle préfère
• ils/elles préfèrent

But:

• nous préférons
• vous préférez

So in ma sœur préfère, the è is the correct stem-changing form.