I'm kind of new to them too but I'll give it a shot. BNR stands for Buy and Replace. That means this it is a promotional Treasury where people can buy an item from the Treaasury or one of the shops featured in that Treasury(depending on the rules layed out) and become a part of the next sale/round.
Each person on the Team or in the Treasury helps promote the BNR Sale Treasury so you get help promoting your item and your shop by participating. You also help promote others the same way. There's lots of ins and outs but the rules are usually put forth in the first post. That's the short version. Does it make sense?
