A season is the limited time during which you can progress your Wunderino Adventure. The length of a season can vary e.g. Christmas season can be for 31 days and Easter season might be for 7 days. Your result when a season ends will be decided by the number of levels and challenges you’ve completed. These will be visible in the “My trophies” section.
When a new season starts you’ll always start at level 1. New seasons will include new rewards and could also mean new challenges and levels to explore.