I mean I'd probably go super generic and say something like "it's a deterministic function which turns a block of data into a usually smaller block of data, usually for comparing equality to the original block of data" which covers most of the uses?

If you ask a generic question, you're gonna get a broad answer, and if you want to draw clarifying questions, you need to ask a more complex question and provide insufficient information to answer it. Even then, making that question something you can easily look up online, and you either know or you don't, doesn't achieve as much as making the question something that you objectively won't know, and have to learn on the spot, as that shows your ability to learn new things including things you can look up on the Internet.