* It's a misspelling: There might be a similar-sounding word you're thinking of. Could you double-check the spelling?
* It's a regional term: It could be a word from a specific dialect or language. Could you tell me where you encountered this word? Knowing the context would help.
* It's a made-up word: Sometimes people create new words, especially in fictional settings.
Please provide more context so I can help you understand what "banuwa" means.