Nada means "nothing." The kids next door will be disappointed if they learn that their lemonade stand has earned them nada.
The noun nada is an informal way to say "zero." If you ask a deli worker how many plain bagels he has, and he answers, "Nada," it means they're out of your favorite kind. If you leave your calculus class completely confused, you can say that you understand nada. Most experts attribute the English use of nada to Ernest Hemingway, who borrowed it from Spanish, in which it means "nothing." The Latin root, nata, means "small, insignificant thing."