The "x of y" thing and the __ ppp thing are both optional. If you want more explanations, though, here they are:
"x of y": (click to open spoiler)
"ppp" is the average posts per player. If you know the total count (always the first number in the post) and how many players have posted (the latest "y"), you just divide them.
7, says non-mod 5 of 5.
Average 1.4 posts per player.
If you're ever curious what "x of y" means, here you go!