When you begin playing (after a length of time), you'll start 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. The game will offer the choice 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.
What can I do if I run out of lives?
You can buy extra lives if you immediately want to continue playing. If you don't want to buy them, a new life will be added to your heart-meter in 30 minutes.
Ask your friends for help
Another great way to get some extra lives and save any precious Gold Bars is to ask for help from your friends.
Just tap on the heart icon on the top of the map screen, and then on Ask friends button, and you'll be able to ask your friends for some help.