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 FAQ, Tabs and Shared Content in the Main Content area and Stats and Quotes, Localist, Twitter and Facebook in the Right Sidebar area.
Here is an example of a Three Column Layout in edit mode:
Changing the layout of a page is easy -- here's how: Changing a Page Layout.