In a double-elimination tournament, any player or team that loses two games is eliminated from the tournament.
Players that lose their first game are dropped into what's often called a "loser's bracket." This is represented on the tournament screen by the lower half set of games.
The winner of the "winner's bracket" plays the winner of the "loser's bracket" in a championship game. In a double-elimination tournament, it's possible for there to be either two championship games. This happens if the winner of the winner's bracket loses the first championship game, they still only have one loss, so another game must be played to determine the final winner.