If you're creating a knowledge graph with many tables, you may want to add descriptions to tables, to make sure users understand what is included in each table. The descriptions will show up in the sidebar of Graph tab:
In order to set up these descriptions, switch back to Data tab, and edit details of your table:
Type the description for each table. Keep it brief, to make sure it won't take too much space in the graph tab. After you're done editing, click Save to save your changes.
Switch back to Graph tab, and you'll see that the description for your table is now updated.
If you'd like to remove the description, repeat the process, but this time remove all text in the Description field. Click save, and table description won't be displayed anymore.