A hermaphrodite is a person (or plant or animal) that has both male and female sexual organs. Hermaphrodites are rare.
This is an unusual word for an unusual condition: being a boy and a girl at the same time. This happens to a small number of people who have the reproductive organs of both men and women. In appearance, a hermaphrodite might look more girlish or boyish, but they're kind of both. This word also applies to animals and plants, which can have both male and female equipment, too.