Penetration testers and cybersecurity analysts often get into the situation of having to do repetitive work that takes away precious time from their active focus. Examples of such situations can be scanning targets, doing intensive enumeration, subdomain discovery, reconnaissance, and more.
This is where programming languages like Python become extremely useful. Mastering Python allows you to take your hands off these repetitive and mundane tasks, automate them through code (and make them faster) so that you can focus on the really mentally challenging aspects of your penetration testing and cybersecurity projects.