The pronunciation depends entirely on the context. It could be part of a longer word or name, and its pronunciation would depend on that context.
For example:
* Uzbekistan: Pronounced "ooz-bek-ih-stan"
* Uzbek: Pronounced "ooz-bek"
* Uz: In the name "Uz," it would likely be pronounced "ooz"
So, without knowing the context, it's impossible to say how to pronounce "Uz."