Galactic Seasons work in a similar manner to the typical 'battle pass' format used in many live service games, with the difference that it is completely free.
Game Update 6.3 launched in Star Wars: The Old Republic earlier this week, bringing two major new additions for content-hungry fans to sink their lightsabers and vibroblades into - a brand new Flashpoint, Secrets of the Enclave, as well as a brand new persistent progression system called Galactic Seasons.