Okay, kiddo, so Māra is a big bad guy in Buddhist stories. Just like how some cartoons have bad guys who try to stop the good guys from doing good things, Māra tries to stop people from achieving enlightenment and becoming really good people.
Māra is kind of like a bully - he teases and tricks people into doing bad things or not doing good things. He sometimes appears as a scary monster or demon to scare people or make them feel afraid. But in reality, Māra is just a representation of our own negative thoughts and feelings, like jealousy, anger, or doubt.
Buddhists try to be aware of these negative thoughts and feelings and not let them control them. They try to practice mindfulness and meditation to overcome them and become more compassionate and peaceful. And in the stories, the Buddha was able to defeat Māra and become enlightened, which is the ultimate goal of Buddhism.
So, remember, Māra is just a representation of negative thoughts and feelings, like a bully, and Buddhists work hard to overcome them and become really good people!