Learn Portuguese (Portugal): Aconselho-te a descansar mais.

In Portuguese, the verb aconselhar (to advise) requires the preposition a when you are advising someone to do an action. The pattern is aconselhar alguém a fazer alguma coisa (to advise someone to do something).

Can I use the subjunctive here and say Aconselho que descanses mais?

Yes, absolutely! Both structures are common and mean the exact same thing. You can either use an object pronoun + a + infinitive (Aconselho-te a descansar) or que + the present subjunctive (Aconselho que descanses).

Why is the pronoun -te attached to the end of the verb instead of before it?

In European Portuguese, object pronouns like -te usually attach to the end of the verb with a hyphen in simple affirmative sentences. They only jump before the verb if a "magnet" word (like não, já, or a question word) pulls them there. Since this sentence just starts with the verb, -te stays at the end.

How would this sentence change if I were speaking formally?