Reverse places changes how locality levels are displayed in the place list. It helps you browse from the broadest jurisdiction down to the smaller locality instead of starting with the town or other smallest level.
On the Places page, choose Options > Reverse places. Choose the same option again to switch back.

For example, a place entered as Town, County, State, Country can be viewed beginning with Country. This is a display option; use the place editor when you intend to change the recorded name. See Place List for editing and Working with Places for the distinction between a place and a place detail.