The Shovel booster allows you to remove one piece or one obstacle layer (e.g., one chain out of two) without using a move.
To use this booster, tap/click on the Shovel icon, then tap/click on the piece or obstacle you’d like to remove.
This booster is very handy for getting access to hard-to-reach tiles or when you don't have enough moves left to complete the level goals.
You can buy the Shovel booster when you're already playing a level, get it as a reward in events or for completing game days, or win it in the Lucky Spin.