A mound is a heap or a pile of material or objects. You can make a mound of clothes by dumping your laundry onto your bed.
The noun mound is occasionally used to mean "a hill," but it most often describes a manmade pile, like a mound of stones or a mound of sand heaped on the beach, or a mound of snow that you sculpt into a rabbit. On a baseball diamond, the pitcher's mound is the little rise on which the pitcher stands to throw the ball. As a verb, mound means to pile something into a heaped shape.