Season Passes offer a varied assortment of rewards that can be obtained by completing Battle Pass Missions. Each week has different free and paid missions. The topmost missions (blue) are ones any player in Eternal Return can complete and claim the rewards to.
The lower half (orange) is composed of missions which can only be completed by players who have purchased the Pass for NP.
All missions grant EP, which is the Pass system's form of experience points. By gaining enough EP, your Pass' level will increase, allowing you to claim rewards.
Rewards can be claimed from the ER Pass' sub tab by the same name:
The maximum amount of EP that can be obtained from a week is listed under that week's tab:
Missions from prior weeks can still be completed regardless of what the current week is.