A bin is a box or other lidded container. You might store onions and potatoes in a vegetable bin in your kitchen.
The noun bin is especially good for describing a specific kind of container, like a toy bin at a preschool or a compost bin on the counter. Bin is more commonly used in Britain than in the United States — a Londoner might say, "Oh, just throw that in the bin," while a New Yorker is more likely to say, "Throw it in the trash," or "Toss it in the garbage." The root word is the Old English binne, "basket."