Coding ..
We mentioned this throughout the entire course. Coding/Programming is a very important thing that you want to learn to really increase your skills as an ethical hacker/penetration tester. You can start with any programming language whatsoever! Here are some of the top Programming Languages for hackers
C
Python
C++
Javascript
Assembly
Feel free to start with any one of them. Once you learn the basics of a programming language you can take a programming course for hackers. I have a course myself for that which is "Complete Python 3 Ethical Hacking Course". Feel free to take that one or any other if you want to boost your skills as a hacker!