It's possible you are thinking of:
* "για" (ya): This means "for" or "to" in Greek, and is used in various grammatical contexts. For example:
* "Γιατί;" (Ya-tee?) means "Why?".
* "Για σένα." (Ya se-na) means "For you."
* "ναι" (ne): This means "yes" in Greek. It's possible you are thinking of a shortened version of "ναι" that sounds like "ya".
If you could provide more context, I might be able to help you understand what you are trying to communicate.