Copying certification is like getting a grown-up to say that a copy of something is just as good as the original.
Let's say you have a very important paper with your name and grades on it. Your mom also wants a copy of it so she can keep it in case the original gets lost or damaged. But how can she be sure that the copy has all the same information as the original?
This is when you can go to someone in charge, like a teacher or a notary, and ask them to "certify" the copy. This means they will check the copy against the original and say that it's a true and complete copy - just like the original.
So, now your mom can keep the copy and it's just as good as having the original. This is important for things like legal documents or certificates that you might need to show to important people or to keep in a safe place.