* It's a misspelling: Maybe the word is meant to be "woo," which can be used to express excitement or approval, like a cheer.
* It's a regional slang: Some slang terms are very localized, and "wuo" could be specific to a certain group or region.
* It's a made-up word: People sometimes invent words for fun, or to have a unique way of communicating with a close group.
If you can provide more context, like where you heard it used or what the speaker was trying to convey, it might be easier to figure out what "wuo" means.