* "Masth" could be a misspelling of "masht", which is a Hindi word for "tasty" or "delicious".
* "Unav" could be a misspelling of "unav" (a word not found in any English dictionary), but it might be intended as "un" (meaning "not") and "av" (which is not a word in English).
Therefore, based on the context, "masth unav" might be intended to mean:
* "Delicious" (if "masht" was intended)
* "Not delicious" (if "un" and "av" were intended)
However, without more context, it's difficult to know for sure what the intended meaning was. It's possible that this is a phrase from a specific dialect or language that is not commonly understood by English speakers.