A personal attack is when someone says unkind or mean things about another person instead of discussing their ideas or actions. It's like when someone gets mad at their friend for not sharing a toy, and instead of talking it out, they call their friend mean names or say things that hurt their feelings.
In a grown-up world, personal attacks can happen during arguments or debates when people disagree with each other. Instead of discussing the issue, one person might start saying mean things about the other person, like insulting their looks or intelligence. This is bad because it doesn't help solve the problem and it makes the other person feel bad. It's important to stay focused on the issue at hand instead of attacking the other person.