If a game stayed the same forever, players would gradually start losing interest in it. Because of this, games like League of Legends and Valorant have what are called seasons which, although they are called seasons, change every 8-10 months in LoL and 2-3 months in Valorant.
Every new season brings with it new content, with that new content occasionally being new playable characters, maps, or new guns and abilities. Additionally, not only does the rank of every player get reset, the rank rewards, as well as the battle pass, get revamped entirely.
LoL has a rather simple concept of seasons, with there being one season every year. However, in Valorant’s case, every episode is divided into three acts, each of which lasts for around two months. Because of this, there’s a new act every two-three months and a new episode every six-seven months.