AStA stands for Allgemeiner Studierendenausschuss (General Student Committee) and represents the social, economic and cultural interests of students. In addition, they are the right contact in matters of politics, sports and international relations.
By the way, the AStA exists and acts according to the Landeshochschulgesetz (Higher Education Act) of Baden-Württemberg (LHG). It is the executive body of the Studierendenschaft der Hochschule Pforzheim, the student body at Pforzheim University. You can find out more in § 65 ff. of the LHG.
You can reach the AStA and the student body at: asta[at]hs-pforzheim.de or by phone at 07231 28 6263. The office is located in the W1 building of the HS PF: W1.1.21.
All further information about the AStA and the student body can be found here.