"Trailer package" or more likely "TOWING package" is an option package your vehicle may come equipped with from the factory. It usually includes a hitch receiver (the square socket on the back of your vehicle), an electrical plug to control the lights on the trailer (might be hidden behind a panel in the rear compartment), an auxiliary transmission cooler, and possibly suspension upgrades.
This is something you can ask your Hyundai dealer. They can look at the option sticker on the inside of your glove compartment door and tell you if you have the towing package. You can also look up the package codes yourself, find out which one is the towing package code for your vehicle, and see if it is listed on the sticker.
Please, resist the urge to glaze your eyes over when you are reading things. It is important that you at least ingest the verbiage correctly so you have the right words in your mind as you learn what they mean.