What does ouach mean in french?

"Ouach" is not a word in French. It's possible there's a spelling mistake or it's a word from a different language or dialect.

Could you please provide more context or clarify the spelling?

For example:

* Where did you encounter this word? (a book, a conversation, a website)

* What was the context of its use?

* Is there any chance it was misspelled?

With more information, I can help you figure out what the intended word might be.