There are 3 types of challenges: Daily, Seasonal and Events. Daily and Seasonal challenges consist of objectives to complete during a match. Completing them will award you with Battle Pass XP. Daily challenges are refreshed on a daily basis, while Seasonal challenges persist throughout the season.
Events are a group of challenges centered around a particular theme and Operators.
Unlocking the Premium Battle Pass gives you access to more challenges on both daily and seasonal challenge slots, increasing the potential daily XP gain.