Other than it's obvious fantasy connotation, it sounds like a game you'd turn your kid away from. It was initially distrusted as a game, and people held the belief that it was a cult movement rather than a fun hobby. It truly is a strange activity, but it has since grown and flourished into one of the most popular RPGs in the world. So what is it?
Dungeons and Dragons is defined by Google as "a fantasy role-playing game set in an imaginary world based loosely on medieval myth."
Created by a group of friends in 1971, it was officialized and published in 1974 and has since spread throughout the world. RPG stands for Role-Playing Game, a classification of games that have been started by D&D. Using dice and good old-fashioned pen and paper, players will describe what they do to another player who's been designated to determine the actions of the environment and NPCs (Non-Player Characters) in the world.
Usually, with one 'DM' (Dungeon Master) and more than one player, the group as a whole carries the story along, the only constants being the universal and predetermined rules of the universe they DM has created to restrict both parties.
But why would anyone play such a game? It doesn't sound fun if the people don't play along with the story. It's easy to complain about everything you can't control, but that's what works with the style. The world is randomized, and the people would act they see fit in their role that they create themselves. This is where people can start an entirely new and completely different life. People treat the game with a variety of roles, and the game as a base can be highly customized to whoever enjoys it.