Medusa is a character from ancient Greek mythology who has snakes for hair and who can turn people into stone just by looking at them. Imagine a scary lady with lots of big snakes instead of hair that can make you feel really still and unable to move like a statue.
The Greeks believed that Medusa was so scary and powerful because of a curse put on her by the goddess Athena. Medusa was originally a beautiful woman with long hair, but then she made Athena angry by doing something that the goddess didn't like. As punishment, Athena turned Medusa's hair into snakes and made her so scary that anyone who looked at her face turned into stone.
Medusa was so frightening that many heroes in Greek mythology tried to kill her, including the famous hero Perseus. He was able to defeat her by looking at her reflection in a shiny shield given to him by the goddess Athena so that he could avoid looking directly at her. When Medusa saw her reflection, she turned into stone.
In modern times, Medusa has become a symbol of fear and evil, and her image is often used in art, movies, and books to represent scary things or danger. So, just remember, if you ever see a lady with snakes for hair, make sure you don't look at her face, or you might turn into stone!