Learn Italian: Chi porta i pasticcini? Li porti tu. - Who is bringing the pastries? You are bringing them.

Placing the subject after the verb puts a strong emphasis on it, which is called contrastive focus. It specifically answers the question of WHO is doing the action, meaning "YOU are bringing them (and not someone else)." If you just said Tu li porti, it would sound like a neutral statement of fact rather than an emphatic answer.

What does li refer to, and why is it placed before the verb?

Li is a direct object pronoun replacing i pasticcini (the pastries), which is a masculine plural noun. Object pronouns generally must go immediately before the conjugated verb. Even though the subject tu was moved to the end of the sentence for emphasis, li stays locked in its standard position right before porti.

The English translation uses the continuous "is bringing" and "are bringing." Why does the Italian use the simple present tense?

In Italian, the simple present tense (porta, porti) is frequently used to talk about definite plans, arrangements, or the near future. While you could use the future tense here, using the present tense makes the arrangement feel immediate and already decided.

Why is the verb porta singular when asking Chi porta i pasticcini?