What I think about the meaning of "Stop Hurting Yourself", is that you shouldn't hurt yourself by trying to commit suicide, doing drugs to hurt yourself or anything like that. Many people try to hurt themselves by doing stupid things like that, but they are only hurting themselves and making the problem worse rather than better.
There was an incident yesterday at school, where there was a girl who was probably going through some difficult times and she decided she was going to drink, she drank alcohol, became drunk and later in 5th period, she started throwing up and about 2 minutes later she fainted and the school staff had to call the ambulance and she was sent to the hospital. Im am not sure how she is doing roght now, but I did here she was okay, but she still hurt herslelf in a bad way. That is why you shouldn't try to hurt yourself.