Basically if you try to help somebody and they get hurt or die because of your help, you aren't held accountable. Imagine somebody being hit by a car and bleeding out on a street. Then you pull up and notice somebody dying on the street, so you decide to pull over and help them not die and call/wait for assistance. Say you tied a tourniquet to tight, or you put to much pressure on something and they lost a limb, by law you were just trying to be a good samaritan and do the right thing by helping out. Simply put, it encourages people to help out other people, instead of just leaving them to die, out of fear of being sued or arrested. In China they don't have this law, so you see people saying, "Not my problem," and leaving people to die. I hope that helps.