"Do you know what heaven and hell are? What are they?"

No, I don't know for sure. I've considered various different theories about it, and there are a great many of them, but there's no way I can know for sure unless I directly experience heaven or hell, is there?

"Do you believe in it"

Yes...in a sort of general sense, but that would need considerable explanation.

No...in the sense of any absolutely specific definition of what it's supposed to be like. I have no direct experience of my own to go on, so how could I do anything but speculate about it? Other people's opinions can be interesting, but they're not a basis on which I would form a belief. Belief, after all, indicates certainty.

I have some possible theories about it.

Here's one: Heaven could be the most joyful state of consciousness. Hell could be the most painful, unpleasant or despairing state of consciousness. That's one way of looking at it.

Here's another: Heaven could be a state of feeling complete (fullfilled). Hell could be a state of feeling extremely incomplete and unfulfilled, and having no idea what to do about it.

Here's another: Heaven could be the experience of communion with all that one truly loves. Hell could be feeling totally alone, with no positive connection to anyone or anything.

I've seen a few people who were in a heaven-like state of mind, more than a few who were in a hellish state of mind, and a lot of others who were somewhere between those extremes. Most of us are somewhere between.

Are you asking about an afterlife? I think it's likely, it seems very likely to me, but I have no way of being absolutely certain about it...until I die.