Spanish phrase
Si necesita ~, avíseme.
Meaning
If you need ___ please let me know.
When to use it
Offers to be informed if someone needs something. Polite offer of help used in workplace or everyday support, considerate and non-imposing tone.
Example dialogue
Si necesita ayuda, avíseme.
If you need help please let me know.
Gracias, le avisaré si la necesito.
Thank you, I'll let you know if I need it.