best motor for e-revo

i don't get the hole lipo thing what makes them so good?:032: :024: :002:

And what does 1s, 2s, 3s, 4s, 5s and so on mean? :032: :024: :002:

how many of the 3s, 4s, 5s thingies can it take, also how many can a Feigao 540c 8xl take?:032: :024: :002:

almost forgot, what is a UBEC and what does it do?