Note: The Sidebar tab is currently known as the About Me tab on the RTV Dealer Sites and Agent Sites. They function in the same manner though.
The Sidebar tab provides the copy for the Sidebar Module. See Modules under Settings if you're not familiar with that.
If you are using the Sidebar Module in one of your sidebars, then make sure you provide copy here. You can use this sidebar area for anything you choose. Just keep in mind that it shows up on every page of your site.
One option would be to use it as a secondary navigation area - maybe you want to provide a list of links about the area you serve. Another option would be to showcase a client there, or a marketing idea. A third option would be to use the embed feature from an event calendar page to put a list of upcoming events on every page. Use your imagination. You have the ability to name the header and edit the copy to your liking.
IMPORTANT: Even though you put content into this sidebar, it won't show up on your site unless you select a position for it in your 'Settings > Modules.' To position this sidebar, select 'sidebar' in one of the drop-downs ('About Me' for the dealer and agent sites).