What is friction and explain

Friction is the force you get when you (for example) Rub something with another, it's a force that may generate heat and even some resistance. Another example is rubbing your hands together, they get hot, therefore friction is working, without friction you wouldn't be able to stop moving.

Friction is the resistance of mass when on another object.

If we avoid friction, we move faster.

But, in some cases, friction is also good. It is used in car brakes, when something rubs on the wheels to make the wheels stop rolling, or rotating.

Ice skates may be another thing. They provide a little friction on the blades, to be able to stop and to be able to move.