The Wheel of Furtune offers you the chance to win either unlimited lives, diamonds, or coins. All you need to do is tap 'Watch' to watch an ad. Then tap to spin the wheel and claim your reward.
When you have spun the wheel, you will have to wait 10 minutes until the next round. An exclamation mark next to the wheel icon on your map indicates when your next spin is waiting for you.

After every 5 spins, you will receive a bonus gift!