Face cards each count as 10, Aces count as 1 or 11, all others count at face value. An Ace with any 10, Jack, Queen, or King is a Blackjack.  If you have a Blackjack, the dealer pays you one-and-a-half times your bet  unless the dealer also has a Blackjack, in which case it's a push  and neither wins.

While luck certainly does have a part to play in Blackjack, there is a lot of skill that goes into playing the game. How much skill or strategy you use depends on the time and effort you are willing to put into learning these skills. One such skill is card counting-not like by casinos but certainly not illegal.