The Banner Section is similar to the Title Section and it is useful to easily create a story banner without the title text content.
From the background editing toolbar the user can do the following actions:
Add a media content as a background opening the Media Editor through the Change media source button and choose between images, videos or maps.
Change the height of the section through the Fit/adapt content button
Remove the banner section through the Remove button
Once the media content has been added as a background of the section, the editing toolbar changes to enable different functionality depending on the content inserted: as explained here.
Below is an example of an image added as background in the Banner Section: