* KDE Frameworks 5, which is a modularized, tiered set of libraries and runtime components that complement Qt with functionality useful to building apps and shells.
* KDE Plasma 5, a set of shells implemented using Frameworks 5. Plasma Desktop is the most prominent of those. KWin is part of Plasma, FWIW, so sure, it's at 5 now.
* KDE Applications. Not yet at 5, but will increasingly ship ports of individual applications to KF5 over the next releases.
Contrast this with KDE 4 development. KDE 4.0 (which contained all of these things in one) came years after the last major release of KDE 3, thus stopping the world cold for its entire development cycle, and e.g. preventing apps from doing feature releases. Separating these things and releasing them independently means that Plasma continued to make 4.x releases during ramp-up of Frameworks 5 development, KDE Applications kept doing feature releases while Plasma 5 is materializing, and so on. It's just a lesson learned from the last round. It's certainly more complex from a "SKU" perspective, but the net effect on users is not leaving them stranded for years. The effect on developers has actually been increased productivity: Plasma 5 development happening against already somewhat-stable Frameworks 5 instead of starting out at the same time, for example.