When you feel sick and can't get better with rest and medicine from the store, you can go to a doctor to get a special paper called a prescription. This is like a secret code that tells the person at the pharmacy which medicine to give you to feel better.
Some prescriptions are private, which means that you have to pay for them yourself and not everyone can see them. This is different from a public prescription, which is free and can be seen by the government.
So if you go to the doctor and they give you a private prescription, you'll have to take it to a pharmacy and pay for the medicine yourself. And nobody else will know what medicine your doctor gave you because it's private. But remember, taking medicine without your doctor's permission is never a good idea!