Okay kiddo, so you know how when you're sick, your doctor gives you medicine to help you feel better? Well, sometimes the medicine can be really expensive because the company that made it spent a lot of money doing research to make it work.
When the company first makes the medicine, they have something called a patent that says only they can make and sell the medicine. That way, they can charge a lot of money for it because no one else can make it.
But after a certain number of years, the patent expires and other companies can start making their own version of the medicine. These medicines are called "generic" because they aren't made by the original company.
The cool thing is that because the other companies didn't have to spend money on research, they can sell their version of the medicine for a lot cheaper! So, if your doctor prescribes a generic medicine instead of the expensive brand name one, you can still get better and save some money at the same time!