Breakdown of Pede-lhe que fale mais devagar.
falar
to speak
devagar
slowly
que
that (conjunction)
pedir
to ask for
Questions & Answers about Pede-lhe que fale mais devagar.
Why is it que fale (subjunctive) instead of just using the infinitive falar?
When you ask, order, or want someone else to do something, Portuguese usually uses que followed by the subjunctive. While English uses the infinitive ("Ask her to speak"), Portuguese phrases it literally as "Ask her that she speak". The verb pedir (to ask/request) expresses a request for another person's action, which triggers the present subjunctive form fale.
How do we know -lhe means "her" and not "him"?
Out of context, we don't! The indirect object pronoun -lhe is gender-neutral and can mean "to him", "to her", or "to you" (formal). The translation uses "her" based on assumed context, but "Ask him to speak more slowly" would be exactly the same sentence in Portuguese.
Who is being told to ask? Is this a formal or informal command?
Could I use lentamente instead of devagar here?
Yes, mais lentamente (more slowly) is perfectly correct and means the exact same thing. However, mais devagar is much more common and natural in everyday spoken Portuguese when you want someone to slow down their speech or actions.