House edge is a mathematical concept that represents the percentage of each bet that the casino expects to keep over the long run. It's calculated by taking the total amount of money that the casino pays out to players, and dividing it by the total amount of money that players wager. For example, if a casino pays out $95 for every $100 wagered, the house edge would be 5%. This means that for every $100 wagered, the casino expects to keep $5.
House advantage can vary greatly depending on the game or bet that you're playing. Some games have a much higher house edge than others. For example, the house edge for slot machines can be as high as 10%, while the house edge for blackjack can be as low as 0.5%, the lowest house edge. The table games typically have a lower house edge than the slots, this is because a table game require more skill than the slots.