What is it? It's a "special" version of OSX you can install on almost any (relatevely new) PC.
This is a really easy video that explains most of the steps in order to get a running version of OSX on your PC!
A couple of suggestions:
-I've had more luck with iAtkos for new, SSE3+ CPUs.
-Don't try dual booting with Windows right away. If you can, try it on a separate HD before deciding if it works well enough to keep it.
-Does it really work? Yes and no. If you get most of your hardware working, it's only the beginning. With some PCs it might work exactly like a Mac, with other you'll need some tweaking, others are hopeless.
Legal notice: You should only do this if you own a Macintosh