Looking at your recent questions, it seems likely that you are following some sort of tutorial that assumes you already understand certain fundamentals that it isn't explaining.
You may benefit from stepping back and trying some more foundational resources first. For example, this one should help you get your bearings on the terminal by covering some of the basic building blocks that other lessons might gloss over. https://ubuntu.com/tutorials/command-line-for-beginners#1-overview
