Unlike posts, pages in Ghost don't appear in the main feed. They're separate, individual pages which only show up when you link to them. Great for content which is important, but separate from your usual posts.
An about page is a great example of one you might want to set up early on so people can find out more about you, and what you do. Why should people subscribe to your site and become a member? Details help!
Now tell the world what your site is all about.