Okay kiddo, have you ever heard of a ghost or a demon? Well, a dybbuk is kind of like that, but it comes from Jewish folklore.
According to legend, a dybbuk is a wicked and unhappy spirit that can possess a human body. It's basically like the spirit takes over the person's mind and body, kind of like a ghost living inside of them.
Some people say that a dybbuk might be the soul of a person who died and hasn't been able to move on to the afterlife, while others say that it's just an evil entity that tries to take over a person's body for its own selfish reasons.
There are some stories that say that if you're possessed by a dybbuk, you might have strange behavior like speaking in a different voice or speaking in languages you don't normally know.
So, in summary, a dybbuk is a spooky creature from Jewish mythology that is said to be able to possess people's bodies and take control of their minds. It's kind of like a ghost, but even more creepy because it can actually make someone act differently.