What kind of questions do evaluation research answers?

Welcome ;)

Thanks.

The question is not clear to me. Are you asking what knowledge we can get from the evaluation research? Or what questions could be proposed in evaluation research?
For the first question, program evaluation explicates program purposes, activities, and outcomes and generates knowledge about their merit and worth. This knowledge can inform program planning and lead to program improvement. For the second question, evaluation questions guide the methods and tools used to collect data to understand the problem under investigation. Methodologically, evaluation questions focus on varied assessment types. The list of types is not exhaustive nor mutually exclusive but provides a framework for thinking about what kind of evaluation you are doing and what evaluation questions you may need to ask.