If you hover the mouse over a node, member or plate in the renderer, an infotip appears that gives useful information about the object as shown below.
Infotips can be turned on or off by clicking the left hand part of the button at the bottom of the side toolbar. If the button is on but infotips don't appear when you move the mouse over the structure, click the arrow part of the button and check that the "Structure Infotips" option is ticked. Note that you can temporarily turn off infotips while you're working by holding down the I key.
See also Query analysis results.