The settings daemon – process name is xfsettingsd – is an application that runs in the background to apply various settings in the desktop. The application 'listens' to the xfconf channels and applies them when the user changes the setting in a dialog and configures everything on startup.

Normally the process is started by the session manager. If this is not the case, you can manually start the process in a terminal (it will fork to the background) or check if the application is enabled in the auto start application of the session manager.