First of all excuse me if you think its a noob question, but consider me a noob as I am trying to understand.
I've got a couple of questions about mining, (which I think fits in bitcoin section rather than the mining section)
First: Why do bitcoin needs mining?
Second: What do they actually mine?
You are probably best off Googling these exact questions... or search in youtube. What you find there will probably explain faster and easier than what people type in this forum. At least if you just want some quick facts and to know the basics.