Terminology

upon reading the Denon 5800 operating instructions I come across a couple terms I don't know, can someone bring me up to speed on these terms. Thanks in advance.

The instructions say... "Multi-zone 1 is a pre-out with an output level adjustment function." (what is the pre-out role in this?)

"Multi-zone 2 is a fixed output level pre-output." (what does this mean on a practical level?)

I am setting up so I can play outdoor speakers from another input.

Thanks much
Bobnf