The lives show you how many attempts you have to beat a level.
You can have a maximum of 5 lives.
You will lose one life every time you fail a level.
A life can be replenished every 30 minutes.
You can see how many lives you have from the number on the heart-shaped icon on the home screen.
To see how many free lives you have, you can tap on the Heart icon on the "Home Screen."
You can refill your lives at the cost of 900 coins.