Antes de se despedirem, os meus amigos abraçam-se.

Antes de is the normal way to say before when it is followed by an infinitive in Portuguese.

So:

• antes de sair = before leaving
• antes de comer = before eating
• antes de se despedirem = before saying goodbye

If Portuguese uses a full finite clause instead, it normally switches to antes que + subjunctive, not antes de.

Because this is the personal infinitive, a special Portuguese infinitive that can show who is doing the action.

The base infinitive is despedir-se.
But here the subject is plural, so the infinitive changes to despedirem-se / se despedirem.

That -em ending shows they.

This is something English does not have.

The subject is os meus amigos.

Portuguese does not need to repeat it, because:

• the context already tells you who it is
• the personal infinitive ending -em also shows a third-person plural subject

So the sentence means that my friends are the ones saying goodbye.

In this sentence, it is understood as the personal infinitive.

That can be confusing because, with many regular verbs, the personal infinitive and the future subjunctive have exactly the same form:

• despedirem
• fizerem
• falarem

Here, the clue is the structure antes de + infinitive, which points to the personal infinitive, not the future subjunctive.

Despedir-se means to say goodbye, to take leave, or sometimes to part.

It is a pronominal verb, which means the se is part of the verb’s normal form.

You can also add the person being said goodbye to:

• despedir-se de alguém = to say goodbye to someone

In your sentence, that object is not stated, because it is not necessary.

Yes. That is an important distinction.

• despedir alguém = to fire/dismiss someone
• despedir-se = to say goodbye / take leave

So the se changes the meaning quite a lot here.

This is about clitic placement in Portuguese.

In European Portuguese:

• in a normal affirmative main clause, the pronoun often comes after the verb: abraçam-se
• with an infinitive after a preposition, it is very common for the pronoun to appear before the infinitive: de se despedirem

So this sentence shows two very typical EP patterns:

• se despedirem
• abraçam-se

Here it means they hug each other.

The se can be:

• reflexive = the subject does something to itself
• reciprocal = the people do it to one another

With a plural subject like os meus amigos, the natural meaning here is reciprocal:

• os meus amigos abraçam-se = my friends hug each other

Because Portuguese often uses se to express that idea.

So English needs:

• my friends hug each other

But Portuguese can simply say:

• os meus amigos abraçam-se

The reciprocal meaning is built into the pronoun se, and the context makes it clear.

In European Portuguese, possessives are very commonly used with the definite article:

• o meu livro
• a minha casa
• os meus amigos
• as minhas amigas

So os meus amigos is the normal everyday choice in Portugal.

Without the article, the phrase is not impossible, but it is less neutral in standard EP.

Not necessarily.

In Portuguese, the masculine plural can refer to:

• a group of men
• a mixed group of men and women

So os meus amigos could mean:

• all male friends, or
• a mixed group of friends

If the group were all female, you would normally say as minhas amigas.

Because Antes de se despedirem is an introductory subordinate clause placed before the main clause.

Portuguese normally separates that kind of fronted clause with a comma:

• Antes de se despedirem, os meus amigos abraçam-se.

If you put the main clause first, the comma usually disappears:

• Os meus amigos abraçam-se antes de se despedirem.

The present tense here gives a natural meaning like:

• this is what they do
• they hug each other before saying goodbye

So it can describe:

• a habitual action
• a general statement
• a simple present-time description

Portuguese uses the present tense very naturally for this kind of sentence, just like English does in My friends hug each other before saying goodbye.