Google is testing a new folder design on Android. Rather than showing a stack of icons like it does now, Android N's latest beta makes it look like you're seeing inside of the folder, which is filled with a grid of icons. It looks a lot more like a folder on iOS — which is perhaps in some ways more functional, but a lot uglier and less visually interesting.
The new design appeared in the second developer beta of Android N. It's possible that the revamped folders are only in testing for now and won't make it into the final release — which will likely come sometime around October — but it's also very possible that this is the direction Google wants them to head in. Hopefully the Android team reconsiders: the current folders are great and should stick around.
You can see 9to5Google take a deeper look at the new folder design here, just after the one-minute mark: