Good question, @Victor-Rosa
I agree with @SIMON-TAPLIN that the Linux Fundamentals course is designed for people with no background in Linux, where Linux+ is more for those that wish to become Linux admins.
One of the first things you'll learn is that Linux is the kernel which is apart of the operating system and bash is the most common command shell used to interact with the operating system. Bash will also allow you to interact with some 3rd-party software binaries. The Linux kernel gets bundled with software and utilities and we generally refer to that as a 'Linux Operating System' and then you get types of Linux operating systems like Ubuntu, Fedora, Debian, etc which we refer to as Distributions or Distros for short.
That said, for the Pentest+ you will need to know a bit of bash scripting, and some bash commands that will aid you in things like privilege escalation, but there will also be a lot of questions about 3rd-party tools like sqlmap, nikto, nmap, etc.
All that to say, Linux Fundamentals will get you going and then use the Linux+ course and the bash scripting series as a reference for the rest. As a pentester you're going to be using Linux, so there's no time like the present to get comfortable with it.
I feel like I got a bit verbose, but I really hope that helps you out.