Product Overview
"The Robot Operating System (ROS) is a flexible framework for writing robot software. It is a collection of tools, libraries, and conventions that aim to simplify the task of creating complex and robust robot behavior across a wide variety of robotic platforms."
-Open Robotics
There are plenty of resources on how to get started with ROS, and many free tutorials can be found on Robocademy's Top Free tutorials to learn ROS.
Among those tutorials, you can find ROBOTIS' own ROS Tutorial Playlist, and download the free ROS Robot Programming book!