The Two Column Layout is the default layout for standard content pages. It offers left navigation and a wide Main Content area. It is flexible and works well for displaying structured content, images and web parts such as FAQ and Shared Site Content.
Here's what a new, blank Two Column page looks like in edit mode:
Here's an example of the Two Column Layout with content in edit mode:
And here's that same page once it is Saved and Checked In:
Changing the layout of a page is easy -- here's how: Changing a Page Layout.