It's used as a noun. "I heard nothing," for instance. The translation of "There's nothing wrong" above is a bit confusing in that matter, because 'nothing' is used as an adverb here. "Der er ingenting i vejen" literally means "There is nothing in the way." The literal translation of "There's nothing wrong" would be "Der er ikke noget forkert." That's my best guess, at least. Still learning. ^-^
Next up: "Jeg er fra Barcelona" and "Jeg snakker godt engelsk, jeg lerner det fra en bog"