Crowns are one of Fall Guys' in-game currencies. They are solely used for advancing the Crown Rank.
You can earn Crowns by winning shows, receive them as a reward for leveling up during a Season, external promotions (Prime Gaming), and surveys. Some shows might reward more or less than 1 for winning, depending on their difficulty (e.g.: Hard Mode, Squads Show).
On the 1st anniversary of Fall Guys (4 August 2021) a double Crown multiplier was activated, lasting one full day.
Starting from Season 1 Crowns were converted into Kudos at a rate of 3000 per Crown, and are no longer a spendable currency as they got replaced by Show-Bucks.
A 3D Crown, as seen in the Season level rewards tab.