Okay, kiddo! D-beat is a kind of music that is named after a type of drum beat that sounds like "dum-dum-dum-dada-dum-dum."
Now, imagine that you are playing a game with your friends called Red Light, Green Light. When your friend is facing away from you and says "green light," you run as fast as you can towards them. But when they say "red light," you stop as quickly as you can.
D-beat music is like the "green light" part of the game, because it's fast and makes you want to move quickly. But then the "dada" part of the beat is like the "red light" because it's sudden and makes you stop.
People like to dance to this kind of music because it makes them feel like they're moving really fast, almost like they're superheroes! So if you're ever at a concert where they're playing d-beat music, keep your ears open for that "dum-dum-dum-dada-dum-dum" beat, because that's what it's all about!