Aquest vespre volem seure prop del mar i parlar una estona.

Because vespre is a masculine singular noun in Catalan.

• aquest = this, masculine singular
• aquesta = this, feminine singular

So:

• aquest vespre = this evening
• but aquesta tarda = this afternoon, because tarda is feminine

Catalan demonstratives have to agree with the noun’s gender and number.

Not exactly.

• tarda = afternoon / late afternoon
• vespre = evening
• nit = night

So vespre is the part of the day after the afternoon and before full night. In English, evening is usually the best match.

Depending on region and context, the boundaries can feel a little flexible, but vespre definitely points to evening, not just any later part of the day.

Volem is the 1st person plural present tense of the verb voler = to want.

Present tense of voler:

• vull = I want
• vols = you want
• vol = he/she/it wants
• volem = we want
• voleu = you all want
• volen = they want

So volem tells you the subject is we, even if nosaltres is not written.

Because after voler in Catalan, you normally use an infinitive directly.

• volem seure = we want to sit
• volem parlar = we want to talk

English uses to before the second verb, but Catalan does not have a separate word here equivalent to English to in want to sit. The infinitive itself does the job.

So:

• volem seure
• not volem a seure
• not volem de seure

No. One volem can govern both infinitives.

So:

• volem seure prop del mar i parlar una estona

means:

• we want to sit near the sea and to talk for a while

This works just like English, where you can say we want to sit by the sea and talk for a while without repeating want.

Yes, seure is a normal and common verb meaning to sit or to be seated.

A useful distinction is:

• seure = to sit
• asseure = to seat someone
• asseure’s = to sit down

In real usage, the lines can blur a bit depending on region and style, but for learners, this is a good basic way to think about it.

So in this sentence, seure is perfectly natural because it expresses the idea of sitting near the sea.

Because prop normally goes with de:

• prop de = near / close to

So:

• prop del mar = near the sea

Here’s the breakdown:

• prop de + el mar
• de + el = del
• so: prop del mar

Using prop al mar would not be the standard pattern here.

Del is a contraction of:

• de + el = del

So:

• del mar = of the sea / from the sea / near the sea, depending on context

Catalan very often contracts these combinations:

• de + el = del
• a + el = al

So prop del mar literally contains de + el mar, but it contracts to del mar.

Yes. Both are possible:

• prop del mar
• a prop del mar

Both mean near the sea.
A prop de is a very common full expression, and prop de is also correct and natural.

In this sentence, prop del mar is simply a slightly shorter version.

Because Catalan often expresses duration without a preposition.

So:

• parlar una estona = to talk for a while
• esperar una hora = to wait for an hour
• dormir tota la nit = to sleep all night

This is very normal in Catalan. English often needs for, but Catalan often does not.

Here, una estona is functioning as a duration expression: a while.

Literally, it means a little stretch of time or a while.

It is a very common expression for an unspecified short period:

• espera una estona = wait a bit / wait a while
• parlem una estona = let’s talk for a while

So in this sentence, parlar una estona sounds very natural and idiomatic.

The sentence is natural as written, but Catalan word order is fairly flexible.

The given version:

• Aquest vespre volem seure prop del mar i parlar una estona.

is clear and idiomatic.

You could also hear variants such as:

• Volem seure prop del mar aquest vespre i parlar una estona.

That said, putting Aquest vespre first is very natural because it sets the time frame right away: This evening...

Because Catalan often drops subject pronouns when the verb ending already makes the subject clear.

• volem already tells you it is we

So nosaltres is unnecessary unless you want emphasis or contrast.

For example:

• Nosaltres volem seure prop del mar...
  = We want to sit near the sea...
  This might sound more emphatic, like contrasting with someone else.

Without nosaltres, the sentence is more neutral and natural.