Okay kiddo, have you ever heard the phrase "you snooze, you lose"? Well, that's kind of what laches is all about.
Imagine you have a toy that you really love playing with, but you let it sit in the corner collecting dust for a long time without playing with it. Then one day, your friend comes over and says that they've been looking for that exact toy everywhere and they really want to play with it. You say no because it's yours, but your friend gets upset and tells your parents that you're not being fair.
In this situation, your friend could argue that you're being unfair because you waited too long to play with the toy and now it's causing them harm by not being able to enjoy it too. Your friend could say that by not taking action earlier to share or give the toy they were relying on you, but you failed to act, so this is unfair play.
That's kind of like what laches is in the law. It's a legal term that means waiting too long to do something can cause harm to someone else. If someone has been wronged, like if they've been hurt or had something taken from them, and then they wait too long to bring their case to court, the judge might say that they aren't allowed to sue because they waited too long and the people they are trying to sue have lost things like evidence that will help defend themselves, or the situation has changed so much that it's not fair to change it back now.
So, the lesson here is if you have a problem or if someone wrongs you, you should speak up and take action sooner rather than later, or else it might be too late.