Avui vull reservar una taula perquè demà no puc arribar tard.

In Catalan, subject pronouns are often omitted because the verb ending already shows who the subject is.

• vull = I want
• puc = I can

So Avui vull reservar... is perfectly natural. You can say jo vull if you want extra emphasis, but it is not usually necessary.

Avui means today.

In this sentence, it comes first:

• Avui vull reservar una taula... = Today I want to book a table...

Putting avui at the beginning is very common when you want to set the time frame right away. Catalan is fairly flexible with word order, so you could also hear:

• Vull reservar una taula avui

But the version with avui first sounds very natural.

Both ideas exist in Catalan, just as in English you can say to reserve a table or to make a reservation.

Here:

• reservar = to reserve / to book
• una taula = a table

So reservar una taula literally means to reserve a table.

You could also say:

• fer una reserva = to make a reservation

But reservar una taula is direct, common, and very natural.

Taula means table, and it is a feminine singular noun in Catalan.

That is why it takes:

• una = feminine singular a

So:

• una taula = a table

If the noun were masculine, you would use un instead.

Here perquè means because.

It introduces the reason:

• Avui vull reservar una taula perquè demà no puc arribar tard.
• Today I want to book a table because tomorrow I can’t arrive late.

So the structure is:

• main idea: Avui vull reservar una taula
• reason: perquè demà no puc arribar tard

A useful thing to remember is that perquè often means because, while per què (written as two words) usually means why / for what reason.

Demà means tomorrow.

It appears before no puc arribar tard to show when that second part applies:

• perquè demà no puc arribar tard = because tomorrow I can’t arrive late

Catalan often places time expressions early in the clause. That makes the sentence easy to follow.

In Catalan, standard negation is usually formed with no placed before the verb.

• puc = I can
• no puc = I cannot / I can’t

So:

• demà no puc arribar tard = tomorrow I can’t arrive late

This is very similar to other Romance languages like Spanish or French, where a negative marker also appears before the verb.

Arribar means to arrive, and tard means late.

Together:

• arribar tard = to arrive late / to be late

This is a very common expression in Catalan.

Examples:

• No vull arribar tard. = I don’t want to arrive late.
• Sempre arriba tard. = He/She always arrives late.

So in your sentence, no puc arribar tard means I can’t arrive late.

Yes. This is a modal-style structure:

• puc = I can
• arribar = arrive

So:

• puc arribar = I can arrive
• no puc arribar tard = I can’t arrive late

Catalan often uses a conjugated verb followed by an infinitive, just like English:

• vull reservar = I want to reserve
• puc arribar = I can arrive

Here tard works like an adverbial word meaning late.

In:

• arribar tard

it describes how someone arrives.

English does the same thing:

• to arrive late

So although learners may first meet tard as the opposite of early, in this phrase it functions just like late does in English.

In standard Catalan, taula is the normal word for table.

• taula = Catalan
• mesa = Spanish

So if you are speaking Catalan, reservar una taula is the correct choice.

Yes, the accent matters in writing.

• perquè = because
• per que or per què can mean something different depending on context

The grave accent on è helps distinguish it and also shows the stressed vowel quality.

For a learner, the important thing is:

• write perquè as one word with an accent when you mean because

Yes, it is grammatical and natural.

It follows very common Catalan patterns:

• time expression first: Avui
• omitted subject pronoun
• verb + infinitive: vull reservar
• reason introduced by perquè
• negative with no
• common expression: arribar tard

So it sounds like normal everyday Catalan.