From someone who actually plays, roleplay that tends to spiral out of control. The DM tells a story and the players act it out however they think is best. Usually it just becomes chaos.

You have to fight monsters and there's magic and dungeons and IDK I've never played it.

I should actually get around to playing RPGs haha

I've played it only once, so I can't explain the rules in depth or anything like that, but I can explain what it is in general terms.

Dungeons & Dragons, and other tabletop RPGs, are games built around collaborative storytelling. One player, the Dungeon Master, is in charge of deciding upon the setting of the story (as the name imples it's most conducive to medieval fantasy settings), acting as its narrator, and keeping the story moving forward. The other players create and control the main characters. The outcomes of various events that challenge the main characters, including combat, are determined by a mix of dice rolls, character stats, and Dungeon Master decisions as specified by the D&D rules.