Once you link this application to your Dropbox account, an /Apps/PhoneGapSync folder is created in your Dropbox. All the files you move to that folder on your computer will automatically be available in this app. The Dropbox app does not need to be installed on your device. The synchronization process is entirely managed by the plugin.
The Dropbox Sync PhoneGap plugin makes it incredibly easy to write synchronization-based applications: synchronized photo viewer, synchronized notes, etc.