You may want to have this moved to the Southwest forum, but I'll answer anyway: If the route only gives you a number and not an airport code it means the plane is stopping "somewhere" but you don't get off of the plane. You'll stay on your same aircraft while some passengers leave and others join for the continuing segment. If you really, really want to know where it'll stop before you buy check out the Flight Status page and it'll give you the arriving city for each flight number and departure city pair.