It gives him the chance to correct his mistakes. It puts him in charge of his actions. Punishment only tells a child that she is bad. It does not tell a child what she should do instead. So punishment may not make sense to the child.
Punishment usually has nothing to do with what the child did wrong.
Here are some examples of what a child can do wrong. Some types of punishment and discipline are given. Explain that they could get broken or mark up the floor. Explain he may not play with the wastebasket. Give him something he may dump and fill.