Hi, it seems to be a pass card for your grandfather. It translates, as good as my German allows, as:
Area Administration of the NSDAP (ie Nazi Party)
Bartold Community (or organisation)
(Only valid with Camp Control Card during period of absence.)
The bearer of this card, Pole Tadeusz Pietrzak, D.O.B. 5.1.1920 belongs to the Bartold Community, Militsch area, Camp Rudolfsdorf.
He is entitled to visit (or reside), up to a distance of __ Km, outside the Camp for the duration given on his Camp Control Card.
Signed by the Camp leader / stamp / signed by Area leader
Hope that helps.