Alright kiddo, in ancient Greece, many people were attracted to others of the same sex. This means that some men liked other men and some women liked other women. They were called homosexuals.
Back then, it was actually pretty normal for men to have relationships with other men. In fact, some famous Greek philosophers and leaders were known to have male partners. The Greeks thought that love between two men was one of the highest forms of love there is.
Women who were attracted to other women weren't talked about as much, but we do know that some women in ancient Greece had female partners too.
It's important to remember that the way people thought about homosexuality back then was very different than it is now. Some people today still don't accept it, but many people do. Just like anything else, times change and cultures evolve.