How exactly does "movement points" work?

Explain like I'm five. I still don't understand how it all works, what does speed mean and how it affects me and monsters, and how can I tell how many tiles closer can a zombie get to me while I'm reloading or doing certain things, how do I tell how many movement points it's going to take etc. Sorry for my retardation.

Also unrelated but... how do I check how much blood I have lost, or is there no such thing?