A law states how something behaves and explains why. hope it helps.
A scientific law is a proven fact that cannot be changed. Unlike a scientific theory, which would be based on a single hypothesis or observation. An example of a scientific law would be the law of gravity-- everything that goes up must come down. An example of a scientific theory would be the Big Bang Theory created by Charles Darwin-- it has not been proven as a law because no one was alive when the earth was created, therefore no one truly knows how it came into existence. Hope I helped!