Selection Pane is to be used if you have multiple objects on the sheet and you need to select one.

Let's say that there are four charts that are on top of each other, and you're only able to see the top chart. When you click on Selection Pane, a window will open on the right side that will list those charts by name. Next to the name of each chart will be a small icon of an eye. By clicking on this eye you can show and hide the chart of your choice.
If you want to see the bottom one, click on the eye icon or the other three and they will disappear. If you want to see them again, just click on the eye icon again and they will appear.

This can be used to save space.

Hope this helps. :)

-- Selection Pane is very easy and quick tool to show or hide pictures and other objects, and sorting them as well.

-- Go to the Page Layout, Selection Pane tab.

In the selection pane window you will see a list of objects that are on your worksheet. The list shows visible and non-visible (Hidden) objects.

Each Object has a small picture beside it showing either an Eye (Visible) or a Window (see through), this indicates the visible status.

- Click on an eye to hide an object,

- Click on a blank pane to unhide the object