to serve you, to help yourself to, to be of help to you
Permíteme servirte.
Let me serve you.
— Parásitos (2019)
Servirte.
To serve you.
— Devdas (2002)
Vuelve a servirte, hijo.
Come back and serve yourself, son.
Espero servirte de ayuda.
I hope this helps.
— 8½ (1963)
¿En qué puedo servirte?
How can I help you?
— Un día de furia (1993)