El cotxe de la meva mare és al garatge perquè avui plou molt.

Because cotxe is a masculine singular noun, so it takes the article el.

A few basic patterns:

• el cotxe = the car
• el llibre = the book
• la casa = the house

In Catalan, the article has to match the noun’s gender and number.

Catalan normally shows possession with de, not with an English-style ’s.

So:

• el cotxe de la meva mare = the car of my mother = my mother’s car

This is one of the most normal and common ways to express possession in Catalan.

In standard Catalan, possessives usually go with a definite article:

• el meu pare = my father
• la meva mare = my mother
• els meus amics = my friends

So la meva mare is completely normal.

Also, meva agrees with mare, which is feminine singular:

• meu for masculine singular
• meva for feminine singular

Al is a contraction of a + el.

So:

• a + el = al

In this sentence, al garatge means in the garage or at the garage, depending on how you translate it naturally into English.

This kind of contraction is very common in Catalan.

Because Catalan often uses a for location where English uses in or at.

So és al garatge is a very natural Catalan way to say is in the garage.

You may also sometimes see en el garatge, but al garatge is very common and natural.

In standard Catalan, ser is very often used for simple location:

• El cotxe és al garatge

That is a normal, neutral way to say where something is.

You may also hear està al garatge, especially in everyday speech, but és is very standard here. Catalan does not use ser and estar exactly the same way English speakers may expect.

Because perquè means because.

It is written:

• as one word
• with a grave accent: è

Compare:

• perquè = because
• per què = why / for what reason

Examples:

• No surt perquè plou. = He/She isn’t going out because it’s raining.
• Per què plou tant? = Why is it raining so much?

There is no separate word for it here.

Catalan weather verbs are usually impersonal, so plou by itself means:

• it rains
• it is raining

English needs a dummy subject, it, but Catalan does not.

The same happens with:

• neva = it is snowing
• fa fred = it is cold

Because Catalan often uses the simple present for something happening right now, especially with weather.

So:

• avui plou molt = today it’s raining a lot

Catalan does have a progressive form:

• avui està plovent molt

But it is less necessary than in English. The simple present is very natural here.

Here, molt means a lot or heavily.

So:

• plou molt = it rains a lot / it is raining heavily

A useful thing to remember:

• after a verb, molt often means a lot
• before an adjective or adverb, it often means very

Examples:

• plou molt = it rains a lot
• molt gran = very big

Yes. Catalan word order is fairly flexible.

Avui plou molt is very natural, but other placements are possible depending on emphasis, such as:

• Plou molt avui

Putting avui before the verb is a very common neutral choice.

A rough English guide:

• cotxe: the tx sounds like ch in church
• garatge: the tg sounds like j in judge

Very roughly:

• cotxe ≈ KO-cheh or KO-chuh, depending on accent
• garatge ≈ ga-RA-jeh or guh-RA-juh, depending on accent

The exact vowel sounds change a bit across Catalan varieties, but those consonant sounds are the key thing to notice.

The accent helps distinguish és from es.

• és = is
• es = a pronoun, as in es diu = he/she is called

So the accent is important because it marks a different word.