The editor area is a section of the workbench window reserved for editors. Views can be anywhere on the workbench, except in the editor area.
The IDE lets you rearrange views and editors so they're beside each other (tiled), or stacked on top of each other (tabbed).
You use editors to browse or change the content of your files. Each editor in the IDE is designed for working with a specific type of file. The editor that you'll likely use most often is the C/C++ editor.
The C/C++ editor is where you write and modify your code. As you work in the editor, the IDE dynamically updates many of the other views (even if you haven't saved your file).