over sb's head

over somebody's head ( something too deep or complex for someone to understand) — выше чьего-л. понимания; недоступно пониманию; очень сложно для понимания

Example: That politician's speech just went way over my head. Did you understand a word of what he was saying?

Similarly
beyond sb's understanding

Example: That politician's speech is just beyond my understanding'

(it) beats my time — это выше моего понимания
see
[beats me]