It’s a simple concept: when you create a link from page A to page B, page B will also reference page A. With traditional hyperlinks, page B wouldn’t know about page A unless you explicitly link it back.
When you create a doc for Orders, and mention Products, a Products page will be created or updated with a backlink.
This is a challange for the writer (where does this go?) and for the reader (where can I find this?).
A fork of the script is also available as a GitHub Action, which you can configure to run whenever your wiki is updated. Note-link-janitor indexes all your wiki style links, and creates a References section on the bottom of each page with backlinks.