There are two types of Passes available that can be purchased in the Battle Pass tab:
Unlock premium rewards up to the current Battle Pass level.
Battle Pass Bundle
Get the Battle Pass, and unlock the next 25 levels for the season instantly. If you have already played through the Battle Pass, purchasing this bundle will add twenty-five levels to your current Battle Pass level. For example, if you are a Level 10, buying the bundle will add 25 levels, making you level 35 in the Battle Pass. It cannot be purchased as soon as you reach level 76, because you cannot buy levels after level 100.
Progression & Rewards
While playing, you will receive Stars. For every 5000 XP you get, you will earn one star. You also gain stars by completing challenges or picking up treasure packs. By accumulating 10, you gain 1 Battle Pass Level that will then unlock the rewards set for that level.
Rewards are divided into two tiers: the Free and the Premium tier. All players can get the rewards from the Free tier of the Battle Pass while items behind the Premium tier are only for players who purchased that season's battle pass. Rewards include Legend and Weapon skins, Banner Frames, Badges, Skydive Emotes, Loading Screens and Music Packs. The Premium tier also grants players 1200 Apex Coins, enough to purchase the next season's Battle Pass, and 1200 Crafting Metals, enough to craft a Legendary cosmetic. It also normally grants a player 2 legendary legend skins. As soon as you purchase the premium Battle pass, you can purchase levels with Apex Coins. You cannot purchase levels after level 100. Battle Pass levels per season are capped at 100 with a bonus 10 levels that give you an exclusive reactive Legendary weapon skin. Battle Pass rewards are exclusive to that season and will not come back again, letting you keep "your OG status".