This article explains explains the benefits of a knowledge-base software. Roam Research: Why I Love It and How I Use It - Nat Eliason It was made for Roam Research but it applies to Obsidian as well.
Backlinks just help to find information. For example, I have a Daily Note for April 29 and I write there “I met [[David Beckham]] today”. Then in the future, if I want to remember when I met David Beckham, I just go to the David Beckham note then check Linked Mentions pane and there it will show that link and so I can easily find the info.
Outgoing link is the link in the Daily Note and the David Beckham note has a Back Link since it is the note being linked to.
Graph View just displays the notes and the links between them. It just helps to visualize the structure of the knowledge base. For example, if I want to find-out what notes link to David Beckham page, I can check that using the Graph View.