When you begin playing (after a length of time), you'll begin the levels with 5 lives shown in the heart-meter at the top of the screen.
If you fail to pass a level you'll lose a life and you'll be given the chance to buy extra moves, or try the level again using another life.
Each time you fail, a life is lost until you completely run out of lives and your heart-meter is empty.
You can buy extra lives if you immediately want to continue playing, or if you would prefer not to you can wait 30 minutes for a life to be added to your heart-meter.
Another great way to get some extra lives without using any precious Gold Bars is to ask for help from your fellow Candy Crush Saga playing friends. If you have linked your game to Facebook you'll be able to ask for extra lives from those people who you know on Facebook who also play the game.
If you don't connect to Facebook or you'd rather not ask your friends for lives, we strongly encourage you to create a King profile instead. King profiles connect you to the Kingdom of fellow players who are all linked for the same purpose, playing and enjoying Candy Crush Saga. You can be sure these fellow players will send and ask for free lives often, so it's definitely a great way to keep topped up.