I don't understand what it is saying. Don't the two highlighted statements contradict each other?
Brad
They do not.
Backup does not backup the data from the device, just settings and apps.
Restore reloads the settings and apps that were saved by backup,
and synchronizes the data
in the iTunes library that you told it in your settings to sync with the device (for example, music, photos, contacts, calendar, movies). If data in the iTunes library has been deleted, iTunes deletes the corresponding data off the device. The library and the device are then in sync, but that may not be what you wish. If iTunes for some reason loses all of your music library, doing a sync will erase all the music on the device. Now you have no music in iTunes or on your device.
Of course, you still have the backup of your hard drive you made the previous evening ;-) ...