Okay kiddo, so let's say you did something wrong and the police want to talk to you about it. Before they start asking you questions, they have to tell you something really important called the Miranda warning. It goes like this:
"You have the right to remain silent. Anything you say can and will be used against you in court. You have the right to an attorney. If you cannot afford an attorney, one will be provided for you."
This is really important because it's telling you that you don't have to talk to the police if you don't want to, and that anything you do say can be used against you in court. You also have the right to a lawyer, even if you can't afford one. This is called your Miranda rights.
Now, a quack Miranda warning is when the police don't actually do it right. Maybe they forgot to say everything they were supposed to, or maybe they didn't say it in a way that you could understand. If they mess up your Miranda rights, it might mean that anything you say to them later can't be used as evidence in court. So it's really important that they do it the right way.