In the game of Blackjack there is a dealer and one or more players i.e the opponents. Although all the players are opponents, they can not harm you in any way. Much of the game is based on luck as well.
Each player is dealt with two cards to start with and the players can then ask for more until they either bust (when the total exceeds 21) or they feel the need to stop. If you get a “blackjack” i.e. a total of 21 you automatically win.
“need to stop” means that if you have a lower card total than 21 and you feel that you might bust on getting a new card, you can stop. If the dealer does not go over 21 and has a total lower than yours, then you win, otherwise the dealer wins and the money is lost. The dealer however must stop at 17. If you have the same card total as the dealer, from 17 and up, no one wins and you get your bet back.
Blackjack (an Ace and either a 10 or a face card) beats a regular hand of 21 (i.e. one not containing an Ace, but comprised of a combination of other cards, such as an 8, a 7, and a 6).