If a child cannot understand their punishment then in almost all cases that punishment is simply abuse, I understand a small pop on the wrist for misbehavior that needs immediate correction but physical punishment runs the risk of creating negative associations to touch (bad touch) that will discolor the perceptions of good touch for their whole life. I should say when verbal warnings and explanations of punishment become viable, easy to understand explanations and asking the child to help in reasoning out the bad behavior are important to show they understand, but being overly verbose or haranguing the child may backfire, they aren't likely to internalize what you are telling them, short and to the point is best. A good tip for this is if you are flustered send them to their room while you collect yourself and consider how you will explain the punishment so that they understand it.