Have you ever tried to speak or write something, but made a mistake and said or wrote a wrong word or phrase? That is called an error. In linguistics, which is the study of language, an error is when someone uses language in a way that is not correct according to the rules of that language.
For example, let's say you want to say "I am going to the store". But instead, you accidentally say "I am going to the car". That would be an error, because "car" is not the correct word for what you wanted to say.
Errors can happen for different reasons. Sometimes it's because the person doesn't know the correct word or grammar rule. Other times, it could be because they are not paying attention or are in a hurry.
Now, it's important to remember that making errors is normal and everyone does it, even adults. That's why it's important to practice and learn from our mistakes so we can improve our language skills.