How is it possible to control the actions of the robot through Python code (not ros2 commands)

[unical1988]

I want to write a publisher listener on two different machines, the first will send data, the second should make the robot say the data or move accordingly.

In the docs such actions are performed through e.g.,

ros2 topic pub --once /speech std_msgs/String "data: hello"
how to do that in Python?
Also how to debug the driver (in the above command) in PyCharm ?