No offense to drunken knight, but i dont understand what he said.
Basically like this:
Each skill has a meter that levels as its used.
Your level has a meter that goes up when your skills level up.
As your level rises so does the requirements to level (meaning it will require more skill level ups to go up a level). As your level goes up, the amount you get for skill levels that dont level often will move it less and less.
For instance my level is 47, when I level say alchemy (37) it will impact my level meter much less than say pickpocket (97) or light armor/1H/archery (all in their 40s). I know this is explained in the link but useful for those that dont want to click links.