I have a quick question what do this thing mean?

[Please, don't let this get after 300. This is designed to be something hard to raise. For every 100 you unlock a tier and get a perk point, which you can spend in sub-tiers for new abilities. Class Mastery advances as you use abilities. I will inform you every time you reach the next 100. Perk points can also be obtained from events and other things of the like.]