Spanish phrase
Te aviso si ~.
Meaning
I'll let you know if ___.
When to use it
Promises to inform someone if a condition occurs. Casual, friendly promise to report results, arrival, or changes, typically used between acquaintances with the speaker offering to initiate contact.
Example dialogue
Te aviso si llego tarde.
I'll let you know if I'm late.
Vale, gracias.
Okay, thanks.