The diagram starts with the first three cards labeled as (A, K, Q) or Ace, King and Queen respectively. The probability of these three options is 1/3 for each. As the diagram continues, Player 1's options are seen as the cards he might receive if he decides to continue betting. Each of these cards has a 1/2 chance. Further down the diagram you see the different outcomes of Player 2's possible decisions. The possible profits and losses if Player 2 decides to bet are displayed. Furthermore, at the bottom of the diagram you can also see the possible gains and losses if players decide to reveal their cards right from the start. Continuing the analysis of the tree diagram, it is clear that if Player 2 has a Queen, he will have no chance of winning the game. This is visible in the left branch of the diagram, since the quantity shown is $0, $0. However, if Player 2 is dealt an Ace, he will always win. Now, if Player 1 has a queen and decides to bluff, Player 2 will call the bet and have an additional $1 at his disposal. This can be seen from the red branch. If Player 1 has a King, he will always check and that is why the Ace/King (AK) branch has a result of $0 compared to the start of the round