Yeah, it's the term used in physics math that tells how bouncy collisions will be.
It's usually in the range of 0 to 1.
0 is no bounce at all.
1 is a perfect bounce. For example a ball dropped should bounce up to its original height.
You can use value greater than 1 for stuff like a super ball or something.
Another thing to keep in mind is the elasticity of both objects is taken to account for the collision.