I have a 97 LY diesel pusher. The battery switch I assume your talking about is near the side door. Off position kills power to the coach batteries so nothing will drain them down and mostly used for storage periods. Anytime your using the RV leave this switch ON.
Did you get the owner manuals with the RV? If not, checkout out the Airstream factory website and many of those can be downloaded. I have both the diesel and gas 1997 manuals. Will be glad to look up anything you might have questions about.