The Battle Pass is a free-to-play seasonal event that rewards you for playing the game. Each Battle Pass Season is composed of Two Different Timers:

• Battle Pass Active: Lasts from two to three weeks. While a Battle Pass is Active you can:
  
  • Complete battles to level it up
  • Purchase levels with gold
  • Claim rewards
  • You can purchase an Elite pass and Claim all Elite rewards.
    
    
• Battle Pass Cooldown: Lasts from one to two weeks. While a Battle Pass is in Cooldown you can:
  • Purchase levels with gold
  • Claim rewards
  • You can purchase an Elite pass and Claim all Elite rewards.
  • Remember that while the Battle Pass is in Cooldown you can't Level it Up by Completing Battles. 

Every Battle Pass Season lasts from three to four weeks (Considering the Active and Cooldown time). Keep in mind that the Battle Pass is an ever-evolving feature and the timing of it might vary from update to update.