This options are used to customize the banner on your site’s pages. You can find this options on Appearance > Theme Options then go to the General Settings tab.
Display header is to select whether you want the pages on your site to display a banner or not. To set up the banner’s height is by using Banner Height option, choosing the banner you’d like to use on Default Header Banner Image, or choose to have a different banner on a post/page by turning on/off the Use Default Banner Image on Single Post/Page ? option and choose a default single post banner on Default Single Post/Page Banner Image.