Tothom vol seure a la terrassa perquè fa bon temps.

Tothom means everyone / everybody.

Even though it refers to many people, it is grammatically singular, so it takes a singular verb:

• Tothom vol = everyone wants

This is similar to English:

• Everyone wants, not everyone want

Because tothom is singular.

vol is the 3rd person singular present form of voler (to want).

A quick comparison:

• jo vull = I want
• tu vols = you want
• ell/ella vol = he/she wants
• tothom vol = everyone wants
• ells/elles volen = they want

So volen would only be used with a plural subject like ells or tots.

Seure means to sit or to sit down.

In this sentence, vol seure means wants to sit.

After a verb like voler, Catalan uses the infinitive directly, just like English:

• vol seure = wants to sit
• vol menjar = wants to eat
• vol sortir = wants to go out

They are related, but not always identical in nuance.

• seure = to sit / to sit down
• asseure’s = to seat oneself / to sit down

In many everyday contexts, seure is the natural and simple choice, and it is completely correct here.

So for this sentence, vol seure is standard and idiomatic.

Catalan a covers several meanings that English splits into different prepositions, including to, at, in, and sometimes on, depending on context.

Here, a la terrassa means something like:

• on the terrace
• at the terrace
• sometimes, in context, outside on the patio/terrace

So you should not translate a word-for-word every time. In place expressions, its exact English equivalent depends on the situation.

Because contraction depends on the article.

In Catalan:

• a + el = al
• a + els = als

But:

• a + la = a la
• a + les = a les

Since terrassa is feminine singular, it takes la, so:

• a la terrassa

No. Terrassa can mean several related things, depending on context.

It can refer to:

• a terrace
• a patio
• an outdoor seating area
• the outdoor tables of a café or bar

So in this sentence, it could mean a literal terrace, but it could also mean the outside seating area where people want to sit because the weather is nice.

Here perquè means because.

It introduces the reason:

• Tothom vol seure a la terrassa perquè fa bon temps.
• Everyone wants to sit on the terrace because the weather is nice.

This is one of the most common uses of perquè.

This is a very common question.

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

Compare:

• Tothom vol seure a la terrassa perquè fa bon temps.
  = Everyone wants to sit on the terrace because the weather is nice.

• Per què tothom vol seure a la terrassa?
  = Why does everyone want to sit on the terrace?

So the accent and the spacing matter.

This is a fixed weather expression.

Literally, fa comes from fer (to do / to make), but in weather expressions Catalan often uses fer where English uses be or simply talks about the weather.

So:

• fa bon temps = the weather is nice / it’s nice out

Other very common examples:

• fa fred = it’s cold
• fa calor = it’s hot
• fa sol = it’s sunny
• fa vent = it’s windy

So it is best to learn fa bon temps as a whole expression.

It can mean both, and context tells you which one is meant.

• temps = time
• temps = weather

In fa bon temps, it clearly means weather.

This is very common in Catalan, so learners quickly get used to deciding from context.

Because Catalan does not need a dummy subject like English it in weather expressions.

English says:

• It is cold
• It is sunny

Catalan usually just says:

• fa fred
• fa sol
• plou
• neva

So fa bon temps is a complete sentence/clause by itself, even though there is no visible subject.

The sentence is natural as it stands, but Catalan word order is somewhat flexible.

The neutral order is:

• Tothom vol seure a la terrassa perquè fa bon temps.

But you could also say:

• Perquè fa bon temps, tothom vol seure a la terrassa.

That version puts more focus on the reason. It is still correct, but the original order is more neutral and everyday.