One framework, two languages by design
ROS, the Robot Operating System framework covered in its own dedicated course on this platform, is built to support both C++ and Python as first-class languages for writing nodes, the individual programs that make up a robot's software system. This isn't an accident of history, it reflects the same split in demands seen across robotics generally: some nodes need to be fast and predictable, others need to be quick to write and easy to modify.
In practice, performance-critical nodes, things like sensor drivers reading data off hardware at high frequency, and control loops commanding actuators, are commonly written in C++. Higher-level logic, like mission planning, coordinating tasks, or building an operator interface, is often written in Python, where development speed and readability matter more than shaving off microseconds.