New to this concept

I just have a few questions. this is all so new to me.. I saw a post that said something about “bunny space” and “kitty space” which I have no idea what that means can someone please help me understand it.

Also do you always act like the little or is it sometimes. Or does it depend?

And another one what happens if the Little gets pregnant do you stop being the little?

I don’t mean to offend just genuinely curious about it! I would love if anyone helps me understand.