The Three Column Layout offers left navigation, a Main Content area in the middle and a Right Sidebar. It is the recommended standard page layout.
It's useful for regular content, images, etc. and web parts such as FAQ, Gallery, and Shared Site Content in the Main Content area and HTML, Localist, and Social Media in the Right Sidebar area.
Here is an example of a Three Column Layout in edit mode:
Here is an example of a Three Column Layout from the College of Liberal Arts and Social Sciences:
Changing the layout of a page is easy -- here's how: Changing a Page Layout.