In Vector drawings, your pictures are made up of points, joined to each other with lines. Like dot to dot puzzles on steroids. Because these dots don't have to stay in the same place, and the lines between them can be changed from straight to curved, rounded to flat.
Now, it is important to know that the 'nodes' or 'points' are the grey or white squares ( the white one is the one selected by clicking on it) . The line or 'path' that shows up deeper red, is the one that you can alter with the menu. The blue squares are 'handles'. Move the blue squares and the node stays in place but the line changes as you do so.
The context box in Studio shows all the options you can use and they are pretty self explanatory.
Why would you need to mess around with nodes? Well, it may be that you want to draw an odd shape. Or perhaps you have traced something and the trace needs tidying up. Or maybe you have a design with way too many nodes that takes forever to cut and you think it would be better with some taken out. Sometimes text needs node editing to weld properly or just to make it look better. Occasionally you may find you have bought a design that you want to or need to modify. Node editing is your friend.
Once you have mastered point editing, you will wonder why you ever found it so hard, I promise!
Moreover, it is pretty much the same in every graphics package you are likely to use. They may have different terminology but the procedures will be the same.