The Display () panel helps you control hidden geometry in your model.
Using the options in the Unhide section, you can unhide hidden geometry. All will unhide all hidden geometry. Selected unhides only the current selection. Last unhides the last piece of geometry you chose to hide.
In Component Edit, you'll see two toggles.
Hide Rest of Model, when toggled on, hides everything in your model except the selected component.
Hide Similar Components hides any components similar to the selected component.
For more information about manipulating hidden geometry see the Hiding Geometry section of Softening, Smoothing, and Hiding Geometry.