The documentation is not clear about what exactly KHA is. And the problem is the documentation not me, I'm an experienced Haxe, C# and AS3 programmer, I probably know about hundreds of libraries in more than 9 years of programming and I can't understand what this is.
So what is KHA exatly?
Is something comparable to OpenFL?
Any example of project that uses KHA and why?

in order:
https://github.com/KTXSoftware/Kha
https://github.com/KTXSoftware/Kha/wiki/OpenFL
https://github.com/KTXSoftware/Kha/wiki/Examples

Kha is a low level sdk for building games and media applications in a portable way.
http://tech.ktxsoftware.com/kha/

It is the most portable thing I know.

I'd like to think of Kha as a Haxe equivalent of SDL. You have access to the lowest level method, then you roll out your own game engine, libraries or whatever on top of Kha.

And the problem is the documentation not me, I'm an experienced Haxe, C# and AS3 programmer

I'm extremely baffled by this. There are pages on the wiki explaining stuff.

Anyways, it's not so much comparable to OpenFL as it is to Lime ( the foundation of OpenFL ).
Kha abstracts in more ways than any other portable haxe tookit does.
Kha doesn't just compile to different languages thanks to haxe, it abstracts GPU and Audio APIs as well. Meaning that instead of just having OpenGL for every platform, you can have DirectX/DirectX12 for windows. Metal for iOS and soonish Vulkan as well. Whereas OpenFL is using OpenAL, Kha can abstract to any audio api, just like it's doing with the GPU apis.

So in short : Kha allows you to create games and applications by accessing GPU, Audio, and Input trough one api for several different platforms/targets.

I believe the backend system is more robust than any existing haxe media toolkit. It's even possible to add Console support to it if the SDKs are provided. Yes OpenFL has Console support as well, but from what I've heard it's far easier to accomplish it in Kha than it was to accomplish it for OpenFL.

Put your haxe experience to good use and start building your games on top of Kha ( or any other application really )! Kha is growing and the potential it has to become a portable beast is only a matter of time ( hell I believe Kha is already king ).

To be fair, I think @fermmm couldn't find the Kha Wiki page, so maybe that's why people usually can't find a quickstart guide for it.

It's not linked directly from Robert's main page -- kha.ktxsoftware.com points to tech.ktxsoftware.com, and on the top bar, the "The Docs" link points elsewhere, and the page doesn't point to the Kha Github page... you can only find it if you google the Kha Github page -> click on the Wiki link on the side panel.

Personally it actually took me a few days to memorise how to get to the wiki page (I didn't bookmark it) Imagine how many people dropped out of checking Kha out at the beginning.

Eh I'm under the assumption that people check the wiki page once they find the repo. If you're 9 years into programming that's the least you'd do.
The blog btw has a big button that says " The Tech" and on that page there are several links to all major repos.

Kha does indeed need a fancy website but that's somewhat underway. But I do believe every link can be found under logical headers.

Anyways I didn't mean it to poke OP. No harm intended.

"The Docs" has a link to the wiki. But, yes, actual website with big, clear links underway.