The Outline View, which you can choose to activate through the
Tools->Views->Outline menu, shows the contents of the current file.
The exact meaning of this depends on the language you are seeing. For Ada, C and C++ files, this is the list of entities that are declared at the global level in your current file (Ada packages, C++ classes, subprograms, Ada types, ...).
Clicking on any entity in this view will automatically jump to the right line in the file, including if your file has been slightly modified since the outline view was last refreshed.
To refresh the contents of the view, select the Refresh
entry in the contextual menu (right-click anywhere in the outline view).
The Outline View is updated automatically after editing, saving the file, or
switching to a different editor.
There are several preferences associated with the outline view, See Outline Preferences.