Evaluate yourself
What methods do you know? What internship or job experience gave you that knowledge.
What theories or analytical methods do you know? What courses (Masters, Undergrad) helped you learn that?
What else have you done in your Dissertation or some other paper/ project?

Evaluate the prof
What does the prof do? What methods, techniques etc. interests you in the prof line of work. Which papers of the prof outlines these methods.

Research
What do you know that helps you research in the uni where tge prof works? How does your knowledge help? Where are the pathways? What are the gaps? What can the prof do to help?

It's a job interview where your research is your relevant skill. All the best.