Depending on the number of rules you choose, and how difficult they are, you will be placed in a bracket with others like you.
The game works by giving you points based on how difficult the rules are for you. However, if one person chooses 3 rules and another choses 13 rules, there will be a wide variation in the number of points they get per day.
For this reason, the game places you in a “bracket”, designated by a color (yellow, orange, green, and purple) that includes people who have about the same number of goals as you, and about the same level of difficulty. There’s still going to be some variation in total possible points, but you can at least have an idea of who your neighbors are.