The quotation occurs in many places. It is incomplete. This seems to be the original form:
Theories of the Political System:... W.T. Bluhm
For the professional student of politics, political theory, in one of its definitions, stands for an abstract "model" of the political order which he is examining, a guide to collection and analysis of political data.
The words "stands for" in the quote can be removed to make the meaning clearer:
Political theory is an abstract model of the political order.
The "political order" refers to politics in general, which is a very complex thing that can't be known completely. The student, in trying to understand that universe, makes a model or map or theory, which represents some aspects of it. It is necessarily simpler than the reality, and in that sense it is abstract. Most of the definitions of abstract apply. The model represents something, but it is much simpler than the thing itself, and that makes it an abstraction.
Just as map is an abstract representation of a territory, with very limited detail, models and theories are very simplified representations of complex things. The root meaning of abstract is that something has been taken away from something else. The theory or model, and the complex reality it tries to represent, are separated from each other.
The quote then mentions that the student uses the model to classify new things that they learn about the political reality, that is, they use the model as "a guide to collection and analysis of political data."
- disassociated from any specific instance an abstract entity
- expressing a quality apart from an object
- dealing with a subject in its abstract aspects: THEORETICAL abstract science