This Lightning Bolt icon is an Event currency called Adventure Energy. This currency type will allow for a Free Spin on the Adventure Events: Star Spin, Food Truck, Jungle Quest, Winter Rescue.
You can win Adventure Energy as prizes from other Events in the game (Collection Events, Town Builder, Team Race Events, etc). You can also receive Adventure Energy from certain Cherry bundles in the Shop.

Once a total of 10 Adventure Energy is collected, you will be able to claim your Free Spin for rewards.

Please note, any unused Adventure Energy will expire and reset at the end of each Event. This means that when the Event countdown timer reaches 0, any remaining Adventure Energy will not carry over to the new Event that begins.

You'll receive a reward of Cherries, Coins, Machine Tickets, and/or Dice Rolls with each Spin. Dice Rolls will help your mascot progress in the Event. Upon successfully completing each level by getting enough Dice Rolls, you'll be able to collect your bonus rewards.