Vull canviar aquesta camisa per una samarreta blava.

In Catalan, the subject pronoun is often omitted because the verb ending already shows who is doing the action.

• Vull = I want
• The ending tells you it is first person singular

So Vull canviar... is completely natural. You can say Jo vull... if you want extra emphasis, contrast, or clarity, but in a normal sentence it is usually left out.

Vull is the first person singular present tense of the verb voler, meaning to want.

Some useful forms of voler in the present:

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

So Vull canviar... literally means I want to change/exchange...

After voler in Catalan, the next verb normally stays in the infinitive.

• Vull canviar = I want to change/exchange
• Vull menjar = I want to eat
• Vull sortir = I want to go out

This works much like English want to + verb, except Catalan does not use a separate word equivalent to to here.

It can mean both, depending on context. In this sentence, because of per and the two clothing items, it clearly means exchange or swap.

• canviar una camisa per una samarreta = exchange a shirt for a T-shirt

In other contexts, canviar can also mean:

• to change clothes
• to change your mind
• to change something

So the exact English translation depends on the situation.

Aquesta means this and it agrees in gender and number with the noun it modifies.

Here it goes with camisa, which is a feminine singular noun:

• aquesta camisa = this shirt

Some related forms:

• aquest = this, masculine singular
• aquesta = this, feminine singular
• aquests = these, masculine plural
• aquestes = these, feminine plural

So the feminine form is used because camisa is feminine.

Because the sentence means this shirt for a blue T-shirt, not this shirt for this blue T-shirt.

• aquesta camisa points to a specific shirt: this shirt
• una samarreta blava introduces a nonspecific item: a blue T-shirt

If you wanted a specific blue T-shirt, you could say something like:

• per aquesta samarreta blava = for this blue T-shirt

So the difference comes from meaning, not grammar.

These are two different clothing words:

• camisa = shirt, usually a button-up shirt or dress shirt
• samarreta = T-shirt

So the sentence contrasts one kind of top with another.

Depending on region and context, clothing terms can vary a bit, but this is the basic distinction.

Yes. In this sentence, per is used in the sense of in exchange for.

• canviar X per Y = to exchange X for Y

So:

• Vull canviar aquesta camisa per una samarreta blava means
• I want to exchange this shirt for a blue T-shirt

This is a very common structure in Catalan.

Normally, no. If you are saying exchange one thing for another, Catalan usually uses canviar ... per ...

• canviar aquesta camisa per una samarreta = exchange this shirt for a T-shirt

Using amb would sound unnatural here for this meaning. Amb usually means with, not for in exchange.

In Catalan, adjectives usually come after the noun.

• una samarreta blava = a blue T-shirt
• una casa gran = a big house
• un cotxe vermell = a red car

So blava follows samarreta because that is the normal adjective position.

Because adjectives in Catalan usually agree with the noun in gender and number.

• samarreta is feminine singular
• so the adjective must also be feminine singular: blava

Compare:

• un jersei blau = a blue sweater
• una samarreta blava = a blue T-shirt
• uns pantalons blaus = blue trousers
• unes faldilles blaves = blue skirts

Camisa is feminine, and the -a ending is a strong clue, but not the whole rule.

In Catalan, many nouns ending in -a are feminine, but you should still learn the gender with each noun. Here:

• la camisa
• aquesta camisa

That feminine gender affects:

• the demonstrative: aquesta
• the article if used: la camisa

Because demonstratives like aquest / aquesta already work like this / that, so you do not normally add a definite article before them in this kind of sentence.

• aquesta camisa = this shirt

Not:

• la aquesta camisa

So aquesta already does the job of pointing out the specific item.

Yes. That would sound more polite or softer.

• Vull... = I want...
• Voldria... = I would like...

If you are in a shop, Voldria canviar aquesta camisa per una samarreta blava may sound more courteous, similar to English I’d like to exchange this shirt for a blue T-shirt.

A simple approximate pronunciation is:

vool kahn-zhyar ah-KES-tuh kuh-MEE-zuh peh roo-nuh suh-muh-REH-tuh BLAH-vuh

A few helpful notes:

• ll in vull sounds like a y sound in many varieties
• c in canviar before a is a hard k
• ny in canviar is like the ny in canyon
• tx does not appear here, but blava has a normal b-l
• stress:
  • aQUESTa
  • caMIsa
  • samarREta
  • BLAva

Pronunciation varies across Catalan-speaking regions, but this should help you recognize and say the sentence.

The given order is the most neutral and natural:

• Vull canviar aquesta camisa per una samarreta blava.

Catalan word order is somewhat flexible, but changing it usually adds emphasis or sounds less neutral. For a learner, this standard order is best:

1. verb of wanting: Vull
2. infinitive: canviar
3. object being exchanged: aquesta camisa
4. item wanted in exchange: per una samarreta blava

So yes, other orders may exist in context, but this is the normal version to learn first.