Okay kiddo, pharmakos is a fancy Greek word that means "a person who gets blamed for bad things and is sacrificed to make things right."
Imagine your class did something bad like drawing on the walls. Even if you did not do it, the teacher might punish the whole class. This is because the teacher wants to make sure everyone learns to behave properly.
In ancient Greece, when bad things happened such as famine or disease, people believed it was because someone in the community had done something wrong or offended the gods. They needed to make things right by finding and punishing that person.
They chose a pharmakos, someone who was considered "impure" and blamed them for all the bad things. This person would be banished or even sacrificed to the gods. It was believed that this would appease the gods, and everything would be okay again.
So, in summary, a pharmakos was a person blamed for bad things and punished as a way to make things right with the gods. But we don't do this anymore because we now understand that it's not right to blame innocent people for things they did not do.