Table of contents allows users to quickly navigate a guide. It's useful for complex guides and instructions people might be coming back to often.
When the table of contents is enabled, it can be opened and closed with the icon in the top left of the media pane (or in the guide's footer on mobile). It can be displayed as a tree or a flowchart.
You can add the table to individual guides or enable it for an entire knowledge base. There's one in this guide, so you can see how it looks.