Hellenism is a modern religion that some people follow today. It's based on the ancient Greek religion, which is what people in Greece believed a really long time ago.
Imagine that you're playing a game with your friends, and you're all pretending to be ancient Greek gods and goddesses. You might be pretending to be Zeus, who was the king of all the gods, or Athena, who was the goddess of wisdom and war. In Hellenism, people actually believe in these gods and goddesses and think they have the power to help and guide them in their everyday lives.
Some Hellenists believe in sacrificing things to the gods, like food or drink, to show their respect and ask for their help. They might also pray to the gods and goddesses or do rituals to honor them.
Hellenists also try to live their lives in a way that the gods and goddesses would approve of. For example, they might try to be brave like Athena or fair and just like Zeus. They believe that by doing this, they can become better people and make the world a better place.
Overall, Hellenism is a way for people to connect with the ancient Greek gods and goddesses and live their lives in a way that honors them.