In the Blender Python for Artists course section on functions Victor points out that displaying the python console is different for Mac and Linux, there isn't the "toggle system console" menu entry provided in Windows. Instead you must start Blender from a text console and that window will display console messages as you use Blender as in the image below
In kubuntu you can edit the Blender entry in the Application Launcher to start in a console by setting the "Run in terminal" option in the Advanced properties as shown below