Every week, there's a weekly challenge consisting of five levels, each taken from the main game, but all with the same gimmick (this can be anything really, but it's normally something that changes up the physics, gameplay, or level design itself). You simply need to play and finish the five challenge levels, and do this every week for 16 weeks. This is a long time, but don't let it daunt you; it's an absolute blast, and you should really go for "Conqueror" and "MBFFs" in the process of this for max efficiency. This achievement on its own, however, is quite easy. It just takes a lot of real-world time. You can see your total progress in "My Marble" for the "Jade" marble.