German phrase
Welche Kenntnisse haben Sie in ~?
Meaning
How much do you know about ___?
When to use it
This asks about expertise. It is polite and suits work or hobbies.
Example dialogue
Welche Kenntnisse haben Sie in der Fotografie?
How much do you know about photography?
Ich habe Grundkenntnisse und arbeite oft mit einer Spiegelreflexkamera.
I have basic knowledge and often work with a single-lens reflex camera.