Spanish phrase
Si necesitas algo, ~.
Meaning
If you need anything, ___.
When to use it
Offers help if the listener needs something. Common polite or casual offer to invite requests for assistance, tone varies with phrasing.
Example dialogue
Si necesitas algo, avísame.
If you need anything, let me know.
Gracias, te avisaré si lo necesito.
Thanks, I'll let you know if I need anything.