The game of Blackjack is built on both luck and strategy. You have to get the right cards, but you also have to know when to stop. The objective of the game is to get a better hand than the dealer: your only opponent, without going bust (going over the number 21).
Once you stand, the dealer will reveal his face down card and continue to hit until he either gets a better hand than you, in which case you lose, or until he busts, in which case you win.
You can choose to "split" when you are dealt two of the same cards. This will split the pair up and each will be played as a separate hand. So essentially, you are playing two different hands at the same time, but your bet will double as well. If you win one hand, you will come out even. If you win both hands, you will double your money.