It's a small kitchen appliance that you use to take the air out of freezer bags when you are freezing food. It comes with a roll of bags that you can cut to whatever size you need. You put your food in, place the edges of the bag around the suction nozzle, press a button and voila! The air is all sucked out. You then press another button and the bag is sealed with heat along the edges and then you can toss the food into the freezer.
I've had mine for years and use it to divide things into two person portions. I also use it for freezing cheese and blanched summer vegetables or berries that I use during the winter. It's really handy and a great item for saving money