Learn Spanish (Latin America): Es muy peligroso; no les entregues el maletín. - It is very dangerous; do not hand the briefcase over to them.

In Spanish, pronoun placement changes depending on whether a command is positive or negative. For positive commands, you attach the pronoun to the end of the verb (like entrégales). But for negative commands, pronouns must go between no and the verb. That is why it is no les entregues.

Why does entregues end in -es when the infinitive is entregar (an -ar verb)?

When you give a negative command to tú (informal "you"), Spanish swaps the usual vowel endings. Because entregar is an -ar verb, its negative command takes the -er/-ir ending -es. (A positive command would just be entrega).

Why is there a "u" in entregues?

It is there to keep the pronunciation correct! The verb entregar has a hard "g" sound (like in "go"). If we just added the -es ending to make entreges, the "g" before the "e" would make a soft sound (like an English "h"). Adding the u creates gue, which keeps that hard "g" sound intact.

What does les mean in this sentence, and who does it refer to?