Imagine you and your friend were playing with toys and suddenly your friend takes away your favorite toy without telling you. You don't like it and you feel sad about it. But you don't take any action about it and keep quiet. After a while, you decide to ask your parents for help and they take the issue to the court.
Now, a frivolous lawsuit is similar to this situation but not the right thing to do. It's like taking your friend to court for taking your toy without permission. The court would waste a lot of time and effort on such a small issue that could have been easily fixed by talking to your friend or finding a different solution.
A frivolous lawsuit is when someone sues another person for reasons that are not reasonable or valid. Sometimes people do this just to harass or inconvenience the other person. For example, if someone sues their neighbor for playing music too loud at midnight when they were not even in town that night, it would be considered frivolous.
Generally, frivolous lawsuits are seen as a waste of time, money, and resources for everyone involved- including the legal system. Therefore, it's always better to try and solve disputes in a non-legal manner before taking the issue to court.