Hi
it is a document that you can get from your Kreisverwaltungsreferat (
here are the infos.).
Will cost you 13€ and takes about 10 days. Munich City Council can only produce them for Munich residents, otherwise apply in your town of (German) residence, if you need one for Germany and do not live here you have to apply to the central Bonn office (Bundeszentralregister).
It is a summary of your criminal record (should you have one) with restrictions regarding spent offences (but that is a bit detailed for here).
Certain employers (state organisations, some emplyoment agencies which deal with government agencies/non-governmental organisations, banks, airlines, schools...) request these, not all do and you can also be requested to get one from your country of orgin/countries of previous residence.
Katrina