Honda Accord Hybrid or Honda Accord Plug in Hybrid

Hi folks, I just register here after seeking help all over internet and still confuse about this hybrid term.

Firstly, I am completely noob in automobiles. We don't have car in my whole family. So, I don't have any idea what to see while seeking for car to buy.

I just started doing job and may be i would be able to buy my first car.
I recently start gathering information about cars and came across this Honda Accrod hybrid and Accord pulg in hybrid. I was reading about it and found that Honda Accord give 50MPG in city and 45MPG on Highway.

I try to understand this MPG but i did not find proper answer so could anyone please tell me how much MPG is equal to how much average in Kilometer.

Which fuel used in honda accord hybrid? Petrol, Diesel or something else?
I read somewhere that it run on electric motor. What does it really mean? Is it mean that we can charge car battery with electricity and run car?

And on what source a purely hybrid car run on?

If my question is too stupid then pardon me.