this person say's it best.
When someone mentions that they wrapped the meat to rest, they mean wrapped in aluminum foil to hold onto the juices (and may also add some liquids for foiling), then towels to insulate, then often, into a cooler for more insulation. I recommend a double layer of foil for most meats, especially if foiling ribs for 3-2-1 or 2-2-1. The purpose is to allow the meat to slowly cool for better redistribution of the natural juices in the meat, and it also allows the meat to continue cooking for a period of time allowing for more tenderization of lesser cuts such as the beef brisket or pork shoulder cuts like boston butt or picnic. BTW, I rarely use just foil for either purpose, opting for a foil-covered pan in most cases...much less risk of leakage from the foil, and easier to handle as well, plus, you can preheat the pan for even longer resting periods with greater heat retention.