The context menu is very common in any program. It appears by pointing to a certain object and clicking the right mouse button and it is called "contextual" because the options it presents depend on both the object pointed to with the cursor and the process or command that is performing. Notice in the following video the difference between contextual menus when you click on the drawing area and when you click on a selected object.
In the case of Autocad, the latter is very clear, since it can be combined very well with the interaction with the command line window. In the creation of circles, for example, you can press the right mouse button to obtain the options corresponding to each step of the command.
Therefore, we can say that, once a command has been started, the right mouse button can be pressed and what we will see in the context menu are all the options of that same command, as well as the possibility to cancel or accept (with the option " Enter ") by default.
This is a convenient, even elegant, way to choose without pressing the letter of the option in the command line window.
The reader should explore the possibilities of the contextual menu and add it to their work alternatives with Autocad. Maybe it becomes your main option before typing something in the command line. Maybe, on the other hand, it does not suit you to use it at all, that will depend on your practice when drawing. What is remarkable here is that the contextual menu offers us the available options according to the activity we are doing.