ELI5: Explain Like I'm 5

what is an offside in soccer

Offside in soccer is a rule that means if any players from one team are closer to the other team's goal than the ball is (AND the second-to-last player on the other team) then that team CANNOT score a goal. Players must try to stay on the same side of the field as the ball or they might get called offside and can't score.