KK Gamer Cheat Store is, as its name suggests, a store where you can download game cheats. To be specific, you will do so in MOD format. That means that you will find game files with a range of modified parameters.
Search for your game and install the MOD that suits you best
You can find MODs that will give you money, others that give you invulnerability, others that offer you unlimited resources - it obviously depends on the specific video game that you are interested in. You can search for these things by browsing different group catergories or by searching manually.
Right, so you know that these stores are not as transparent as we would like them to be, so it is not that often that we are able to just click and download a file. As for KK Installer, you have to get the coins that will give you credit for downloads and you can only get these by downloading the sponsored applications they offer. So, if you don't like the sound of that system, go for something else, like Lucky Patcher or Lulubox, both of which you can find on Malavida.