It's a limited-time event pass with numerous rewards you receive for playing the game. Complete its daily Tasks and weekly Challenges (longer but more rewarding Tasks) to get Battle Pass points to unlock new levels.

By purchasing the Premium Pass, you can unlock even more rewards including new items and items marked as "Unique" -- you won't find them anywhere besides the current Battle Pass season. You can also purchase levels to catch up or to reach items you like faster.

Join the Royal Club to double the Battle Pass points you get from Tasks and Challenges.

The Premium-Plus Pass also unlocks a number of Shortcut Challenges that are much easier to complete. Purchasing Premium options is valid for only 1 season.