Explanation of the concepts of shell commands, command lines, and terminal operations under Linux?

Traditional Linux does not have a graphical user interface, that is, without a mouse, it can only be managed by typing commands one by one.

The Linux desktop version you have installed now comes with a graphical user interface. You can use the mouse to tell the computer what you want to do and let the computer perform corresponding operations.

Because there are many versions of the graphical user interface, I don’t know which version you are using. When a book describes a certain operation (or someone tells you how to operate it), it often tells you what command to use.

To use those commands, you have to find and open a small window on your graphical user interface and type those commands.

The window that is opened is called the "command line window"; the command you type in the command line window is called the "shell command"; "terminal run" means that you run it in such a window.