Well, I would suggest that you try to determine in the paperwork that came with your trailer or on the panels themselves what type and how many panels you have. In addition, you also might find it helpful to know what make and model solar charger was fitted as well. With this info you should be well on your way to mastering your solar setup. Usually the owners manual for the solar charger is a good resource in helping you understand your system.
Now with that out of the way, your solar panels ARE used to charge your batteries. Your batteries provide 12 V to power various systems in your trailer, such as lighting, heating, sound, etc. These batteries can be charged when connected to shore power (120VAC) via a converter, and they can also be charged from your solar panels via your solar charger - at least when the sun shines! How much energy you consume from your battery bank depends on your installation and the various loads you might end up using. Many of us running solar try to be economical when it comes to using energy, so we might replace all the incandescent lamps with lower energy LEDs to save energy.
Hope that's enough to get you started and feel free to ask more specific questions. Enjoy you trailer!
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar