The Hierarchy Tab shows the current structure of your scene. You can use it to navigate through the objects in your scene. Left clicking on an object selects it and its children. CTRL+Clicking on an object selects just the parent object.
You can right click on an object in the list to display a few options:
Zooms in on the selected object. This is especially useful if you can’t find a specific object in your scene. In the basic camera mode, focusing an object causes the camera to rotate around it.
Removes all X-Ray and Solid color effects from selected part.
Resets selected part to its original position.