Any text you type into the content box on the SITE SETTINGS page of your Admin Panel will show up here on every page of your site.  Many people use this space to put in a newsletter sign up space or put their membership banners to online malls like Shabby Lane Shops or Top 100 Sites they belong too.  Any text you put here will automatically wrap around to fit in this narrow column on the left but any images you upload here should not be more then 175 pixels wide or it can distort your design.  Do not upload any images in the content box of your Site Settings page that is wider then 175 pixels wide.