GESTAPO is an abbreviation - the German equivalent of an acronym. It is short for Geheimstaatspolizei. geheim = secret. Staats = State. Polizei = Police.
GESTAPO, and Gestapos is bad usage- you would say Gestapo agents, or men. It was the plainclothes or detective arm of the German SS and derives from the acronym- Geheime Staats Polizei=- Secret- lit,...
They were the secret police force of the Third Reich. They were NOT paramilitary soldiers like the SS (Schutzstaffel) or its predecessor, the SA. The Gestapo was also not a normal civilian police...
They hunted the Jews, hippies, homosexuals, blacks and gypsies for the Nazi's. They usually killed them if they found them. This was in WWII for Hitler.