Després de treballar, la meva amiga va a la piscina per nedar una estona.

Because after després de (after), Catalan normally uses an infinitive when the subject stays the same.

So:

• Després de treballar = After working / After she works
• Després de menjar = After eating
• Després d’estudiar = After studying

This is very similar to English after working, though English can also use a full clause like after she works.

If you want to name a different subject explicitly, Catalan often uses a full clause instead:

• Després que ella treballi... = After she works...

But in your sentence, després de treballar is the normal and natural choice.

Catalan shortens de to d’ before a vowel sound:

• després d’estudiar
• després d’anar a casa

But before a consonant, it stays de:

• després de treballar
• després de dinar

Since treballar begins with tr-, you keep de.

In Catalan, possessives are usually used together with the definite article:

• la meva amiga = my friend
• el meu cotxe = my car
• les seves germanes = his/her/their sisters

This is one of the big differences from English. In English, my replaces the, but in Catalan the article is usually still there.

A few vocative or fixed expressions may drop the article, but in ordinary sentences la meva amiga is the standard form.

Here, va means goes and is the present tense of anar (to go):

• jo vaig
• tu vas
• ell/ella va
• nosaltres anem
• vosaltres aneu
• ells/elles van

So:

• la meva amiga va a la piscina = my friend goes to the pool

This can be confusing because va + infinitive is also used in Catalan as a common past tense:

• va nedar = she swam

But in your sentence, va is followed by a la piscina, not by an infinitive, so it clearly means goes.

Catalan often leaves out subject pronouns because the verb ending usually makes the subject clear.

So instead of saying:

• Ella va a la piscina

Catalan often simply says:

• Va a la piscina

In your sentence, the subject is already stated as la meva amiga, so adding ella would usually be unnecessary unless you wanted emphasis or contrast.

Because anar a means to go to.

So:

• va a la piscina = goes to the pool
• va a casa = goes home
• va a l’escola = goes to school

Here, a is the preposition to, and la piscina is the pool.

So the structure is:

• anar + a + place

Here per expresses purpose, meaning in order to or for the purpose of.

So:

• va a la piscina per nedar = she goes to the pool to swim
• literally: she goes to the pool in order to swim

This is a very common pattern:

• Estudia per aprendre = He/She studies to learn
• Va a la botiga per comprar pa = He/She goes to the shop to buy bread

In many cases, English just uses to + verb, while Catalan often uses per + infinitive.

Yes, va a la piscina a nedar is also natural in many contexts.

Both can express purpose, but there can be slight stylistic or contextual preferences.

• per nedar clearly marks purpose: in order to swim
• a nedar is also common after verbs of movement: go somewhere to do something

So both of these are possible:

• Va a la piscina per nedar una estona
• Va a la piscina a nedar una estona

Depending on region and style, one may sound more natural than the other, but the sentence you were given is perfectly correct.

Una estona means a while or for a little while.

So:

• nedar una estona = to swim for a while

It refers to a short, indefinite period of time, not an exact duration.

Examples:

• Espera’m una estona = Wait for me a while
• He llegit una estona = I read for a while

It is a very common everyday expression.

Because Catalan often expresses duration without a preposition where English uses for.

So Catalan says:

• nedar una estona
• esperar dues hores
• dormir tota la tarda

English usually says:

• swim for a while
• wait for two hours
• sleep all afternoon

This is a normal difference between the two languages.

It is natural and helpful because Després de treballar is an introductory time phrase.

So the comma separates that opening element from the main clause:

• Després de treballar, la meva amiga va a la piscina...

In short sentences, punctuation can sometimes vary, but using the comma here is very standard and makes the sentence easier to read.

Yes. Catalan word order is flexible, though some versions sound more neutral than others.

The original sentence is very natural:

• Després de treballar, la meva amiga va a la piscina per nedar una estona.

You could also say:

• La meva amiga va a la piscina per nedar una estona després de treballar.

That also makes sense, but it places the time phrase at the end instead of the beginning.

Putting Després de treballar first helps frame the whole action in time, which is very common in Catalan.

The sentence already sounds natural, but in everyday speech some speakers might choose slightly different wording, for example:

• Després de treballar, la meva amiga va a la piscina a nedar una estona.
• Quan plega de treballar, la meva amiga va a la piscina a nedar una estona.

A few notes:

• a nedar is very common after movement verbs.
• plegar de treballar can mean to finish work / get off work in everyday usage.

But your original sentence is fully correct, clear, and natural for learners to study.