Usually some sort of tagline or description is placed here.
Sometimes this would be called a sidebar or aside, but it doesn't always have to be on the side to be called a sidebar. Sidebars can be on tops of things, below things, but they are usually beside things – hence it being a called a sidebar.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce nec tellus sed augue semper porta. Mauris massa. Vestibulum lacinia arcu eget nulla. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos.