Welcome to the Candy Crush Saga Community
Do you have a question or need help with your game? Ask the Community.
The Adventure Pass is similar to the Magic Season that ran in the game a time ago.
Complete levels on your Saga map to reach the next tier in the Adventure Pass event.
For every tier you reach you will be rewarded.
You can choose to continue the event with either the free option with smaller rewards or the purchasable option with bigger rewards (Gold Pass).
In most events you'll find the pink circle with an "i" up to the left where you can find more info on how to play it the event.
The screenshot @Elsa posted explains the event quite well:
Let us know if you need any further help!
The is free to download and free to play!
In the Adventure Pass you also have the free option to continue and not forced to choose the Gold Pass.
Since the game is free to play, it features in-game purchases instead to monetize the development, maintenance, support and the making of all new levels and events. However, all purchases are fully optional in the game.