What's meaning of valid for Schengen(-PL)?

I've just been issued a short stay Schengen visa Germany embassy. When I checked it I notice a line of words
"valid for Schengen(-PL)" on top of the visa. My questions are: what's meaning of this? and "can I go to German by holding this visa?"

Thank you.

It means that the visa is valid for the entire Schengen area, except Poland.