How would you describe this in under 5 minutes to a interested friend or family member / layman at a social gathering? If you have the time, make a video, put it on peertube and link to it in your readme. It'll take a few hours or so to do it right, but it might help.
A somewhat superficial way to describe the application is perhaps to call it a more semantic wiki; for example, the application allows you to establish semantically meaningful relations between topics (i.e., defining not only the type of relationship but also what role each topic plays within the context of the relationship). There is much more to the application than just that, but it is an example of how the application allows you to model/express a knowledge domain.