Arduino-CMake, as the name suggests, combines the best of both worlds:

1. Arduino
2. CMake

It is a simple solution to enable developers write Arduino code using their favorite IDEs. While there's nothing wrong with the Arduino IDE that comes along with Arduino, many developers feel like it's missing some valuable features other IDEs do have. And as it turns out, Arduino is also a build system - meaning it could be built using CMake, on any OS.

Further documentation regarding installation and usage can be found in matching pages.