Hyper-V is a computer program that helps you create other little computers inside your main computer. Imagine your main computer is a big house and the little computers are like tiny dolls houses inside it. Hyper-V helps you make these tiny dolls houses and then you can put different things inside them like different games or programs.
But, just like you need a lot of electricity to run a big house, your main computer needs a lot of power to run all these tiny dolls houses. Hyper-V makes sure that your main computer has enough power to make all the little computers work well. It's like having a really smart grown-up who makes sure you have enough toys to play with without running out of batteries!
Hyper-V is a special tool that only grown-ups usually use because it needs a lot of computer knowledge to use it properly. But it's very helpful when you need to do things like testing out new programs or trying out different versions of software.