Sand is a substance that's made of tiny pieces of rock. The sand on some beaches is rough and pebbly, while other sand is smooth and soft. Either way, don't track it into the house.
You can find sand on riverbanks, in flower beds, and in sandboxes, among many other places. Grains of sand are composed of rocks and coral that have been worn down over the years. As a verb, sand means "make smooth with sandpaper." There's also an old fashioned colloquial way to use this word, to mean "determination" or "grit." So you could say, "I'm impressed that she had the sand to travel in India by herself!"