Well, kiddo, the barbary corsairs were a group of people who lived a long time ago in a place called North Africa. These people were very good at sailing ships on the ocean and they used their skills to rob other ships that were passing by. They would take things like money, jewels, and other valuable things that they found on those ships.
Now, the other countries didn't like that very much and they tried to stop the barbary corsairs from doing that. But the corsairs were smart and they knew how to hide from their enemies. They would often hide in little coves along the coast where other ships couldn't find them.
Eventually, some countries decided that they had enough of the corsairs' antics and they decided to fight back. They sent their own ships to North Africa to try and stop the corsairs from robbing more ships. It was a long and hard fight but eventually, the corsairs were defeated and things became safer for the ships that passed by North Africa.
So, in short, barbary corsairs were a group of people who sailed ships and robbed other ships. They were eventually stopped by other countries who didn't like what they were doing.