Chess is a strategic game that is basically a battle on an 8x8 board. The goal is to outthink and outmaneuver your opponent and eventually get checkmate, which is when the other king is trapped and has no legal moves left. I like chess because it always feels different depending on who I am playing.
Modern chess came from older games like chaturanga. The rules evolved and the pieces changed (especially the queen becoming much stronger), which helped shape the version of chess people play today.