Developing software means that you'll interact with the file system of your computer, and you have to understand how it works, how to create files and folder, how to delete, how to navigate, etc.
Understanding the file system (Part 1)
This explains the basics: what is a file, an extension, a folder, etc.
It is of the utmost importance to fully understand this!
Also, since you'll be during the MSc working with Linux, you should also understand how its file system works (it is the same as macOS but rather different from Windows).
Understanding the file system (Part 2)
This explains the basics operations on files and folders: creation of them, deletion, moving, copying, etc.
The part about macOS is more or less the same for Linux.