to tell (him/her/you)
Él te explicará bien qué decirle al procurador.
He will explain to you exactly what to say to the attorney.
Ah, no tenía qué decirle, y lo inventé de momento.
Oh, I didn't have anything to say to him, so I made it up on the spot.
— Cidade dos Homens (2007)
I have something to tell you.
No puedes decirle eso a tu madre, le vas a hacer daño.
You can't tell your mother that, you're going to hurt her.
Tom apenas podía oír lo que Mary intentaba decirle.
Tom could barely hear what Mary was trying to tell him.