Pai Gow is from an ancient Chinese game that used dominoes to achieve winning stacks of two and three. The live casino version uses cards in place of dominoes, but the rules and aims remain. Winning happens by having both hands being superior to those of the dealer. This requires considerable skill and strategy.
Each player receives four tiles and has to combine them into two sets (hands). After every player has done so, the bank reveals its tiles, and also combines them into two sets, following the house rules. To win a game, a player must beat both sets. The bank wins by not losing either hand.