The left menu is very flexible, allowing you to get to administrations screens with fewer clicks and faster load times.
If you click on any of the section labels, it opens the first screen of that section, and the menu section will expand to show the other options.
Hover over any of the section labels and a pop out will appear to show you any of the sub pages in a section. When you click on one, the appropriate screen will be loaded.
If you want to save some extra space in the user interface and hide most of the menu system, click on the collapse menu button at the bottom of the menu.
The menu will collapse to a single row of icons.
If you want to get the full menu back again, click the expand menu icon at the bottom of the menu.