Sidebar tags are a feature that allows admin to specify which tags are displayed in the right-hand sidebar of your homepage. You can also choose in which order these tags are displayed.
To add sidebar tags, you must navigate to
/admin/customization/config and click "show info" beside "Tags". You then can list any tags you want to display, separating each one by commas. These tags will appear top-to-bottom, the order in which you list them.