over your head
Meaning: If something you hear or read is over your head, or goes over your head, you don't understand it because the language or the ideas are too advanced for you.
- I tried listening to a show on the radio about modern physics, but most of it was over my head and I gave up after about ten minutes.
- Jerry told a really funny joke about the economics of the cheese industry, and it went right over Tom's head. He didn't even smile.