Default [Q] Samsung China mobile apps

I have bought a copy of samsung note 8 called "calaxy note 8" and it has an os similar to android,but it's not for sure android since the adb in my computer didn't recognize it .
I'm trying to install apps on this mobile but i can't reach which extension does it accept , i tried .jar , .jad and unfortunately neither worked and files are not recognized in the file manager of the device.
i bought it having the following apps installed : fruit ninja , angry birds , yahoo messenger , opera browser , skybuddy , twitter , and some other games.
but a friend of mine brought another china samsung s4 device and for sure it has the same OS i had but with extra apps installed , so i knew at that moment that the device i have can accept installing other apps rather than those pre-installed.
any suggestions of what type of extensions might this mobile accept for installing apps?