Prima di entrare in piscina, metto il costume e prendo l’asciugamano.

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

• metto = I put on / I wear
• prendo = I take

So io metto and io prendo are possible, but io is usually unnecessary unless you want emphasis or contrast.

Prima di + infinitive means before doing something.

So:

• prima di entrare = before entering / before going in

This is a very common structure in Italian:

• Prima di uscire, chiudo la porta. = Before going out, I close the door.
• Prima di mangiare, mi lavo le mani. = Before eating, I wash my hands.

Because after prima di, Italian normally uses the infinitive when the subject is the same.

So:

• Prima di entrare in piscina, metto il costume...

means Before entering the pool, I put on my swimsuit...

If the subject changes, Italian usually uses a different structure:

• Prima che lui entri in piscina... = Before he goes into the pool...

In piscina is the most natural general expression for to the pool / at the pool / in the pool area, depending on context.

Here, entrare in piscina is understood as to go into the swimming pool / into the pool area, and Italian often uses in without an article in this kind of expression.

Compare:

• andare in piscina = to go to the pool
• essere in piscina = to be at the pool / in the pool

Nella piscina is more specific and usually refers to in the actual pool or in that particular swimming pool.

Not in the English sense of a fancy outfit.

In this context, il costume means swimsuit or bathing suit. Very often you may also hear:

• costume da bagno = swimsuit

In everyday Italian, people often shorten it to just costume when the context is clear.

Italian often uses mettere for to put on clothing.

So:

• metto il costume = I put on my swimsuit

It can sound natural in contexts where English might say I put on or even simply I wear, depending on the situation.

You could also hear:

• indosso il costume

This is also correct, but metto il costume is very common and everyday.

Because asciugamano is a masculine singular noun beginning with a vowel, and il becomes l’ before a vowel.

So:

• il costume
• l’asciugamano

This is called elision.

Other examples:

• l’amico = the friend
• l’albero = the tree

Prendere means to take, while portare means to bring / carry.

So:

• prendo l’asciugamano = I take the towel
• porto l’asciugamano = I bring the towel / I carry the towel

In this sentence, the focus is on the action of taking it before going in, so prendo is very natural.

In Italian, the present tense is often used for habitual actions and routines, just like in English.

So this sentence can mean something like:

• Before going into the pool, I put on my swimsuit and take my towel.

It describes a regular action or a general sequence, not only something happening right now.

The opening phrase Prima di entrare in piscina is an introductory part of the sentence, so a comma is natural and helps readability.

Structure:

• Prima di entrare in piscina, = introductory time expression
• metto il costume e prendo l’asciugamano. = main clause

In short sentences, punctuation can sometimes vary, but the comma here is standard and helpful.

Yes, Italian word order is flexible, though some versions sound more natural than others.

The given sentence is very natural:

• Prima di entrare in piscina, metto il costume e prendo l’asciugamano.

You could also say:

• Metto il costume e prendo l’asciugamano prima di entrare in piscina.

This means the same thing. Putting prima di entrare in piscina first gives a slightly clearer before... frame from the start.

You learn it partly from the article and partly from vocabulary.

Here the articles show it clearly:

• il costume → masculine singular
• l’asciugamano → masculine singular, with l’ instead of il

Also, many masculine nouns end in -o, such as:

• costume
• asciugamano

But article + noun together is the safest way to learn gender.

It is the standard and most common word for towel.

You may also hear:

• telo = towel, beach towel, sheet-like towel

At a swimming pool or beach, telo mare can mean beach towel. But asciugamano is the basic everyday word and fits this sentence perfectly.