I'm seeking advice about where I can read about UU, I'd like to read more about UUism, can you give me some recommendations on it?

Thank you

I tried to explain someone what is UU, but it seems to me so difficult to explain this 'liberal religion' and 'non credential religion' stuff and what's UU objective and all of that.

How can I explain all of that in a simple way, so I can be understood?