Antes da entrevista, o Pedro quer fazer a barba.

Because de + a contracts to da in Portuguese.

Here the structure is:

• antes de = before
• a entrevista = the interview

So:

• antes de a entrevista becomes antes da entrevista

This kind of contraction is very common and normally required in standard Portuguese.

In European Portuguese, it is very common to use the definite article before a person's first name in everyday speech:

• o Pedro
• a Maria

This does not mean the Pedro in English. It is just a normal feature of the language.

This is especially common in Portugal. English does not do this, so it often feels strange at first.

quer is the 3rd person singular of the verb querer = to want.

So:

• o Pedro quer = Pedro wants

After querer, Portuguese normally uses an infinitive:

• quer fazer = wants to do / wants to make

So the pattern is:

• querer + infinitive

Examples:

• Quero comer. = I want to eat.
• Ela quer sair. = She wants to go out.
• O Pedro quer fazer a barba. = Pedro wants to shave.

Fazer a barba is a very common idiomatic expression meaning to shave or to shave one's beard/facial hair.

Literally, it looks like to do the beard, but you should learn it as a set expression.

Portuguese often uses expressions like this for personal care routines. So instead of translating word by word, it is better to understand:

• fazer a barba = to shave
• fazer as unhas = to do one's nails

Portuguese often uses the definite article with body parts and everyday grooming expressions.

So a barba here does not mean a specific beard being singled out in the way English might suggest. It is just the normal Portuguese way to say it in this expression.

Compare:

• fazer a barba = shave
• lavar as mãos = wash one's hands

English often uses my, his, her, etc., where Portuguese prefers the definite article.

In this sentence, yes, that is the natural interpretation.

Without extra context, O Pedro quer fazer a barba normally means Pedro wants to shave himself.

If needed, Portuguese can be more explicit in other ways, but in everyday usage this sentence is understood naturally as Pedro shaving his own face.

A related verb is:

• barbear-se = to shave oneself

So you could also say:

• O Pedro quer barbear-se antes da entrevista.

That is correct too, though fazer a barba is very common and natural.

The phrase Antes da entrevista is placed at the beginning of the sentence as a time expression.

The comma helps separate that introductory element from the main clause:

• Antes da entrevista, o Pedro quer fazer a barba.

This is very natural. With a short introductory phrase like this, the comma is often optional, so you may also see:

• Antes da entrevista o Pedro quer fazer a barba.

Both are possible, but the version with the comma gives a clearer pause.

Yes. That is also completely natural.

Both versions mean the same thing:

• Antes da entrevista, o Pedro quer fazer a barba.
• O Pedro quer fazer a barba antes da entrevista.

The difference is mainly one of emphasis:

• starting with Antes da entrevista highlights the time first
• putting it at the end sounds a bit more neutral

No. It can refer more generally to shaving facial hair, not only a large beard.

So it may be used even if someone just has stubble or needs a clean shave before an event.

If you specifically mean trim the beard rather than shave it off, Portuguese would more likely use another expression, such as:

• aparar a barba = to trim the beard

So:

• fazer a barba = shave
• aparar a barba = trim the beard