It's a VERY old-fashioned word. It shouldn't be part of your active vocabulary. You can know what it means, but you shouldn't try to use it.
"Bunk" means the same thing. It's old-fashioned too, but not quite as old-fashioned.
It means nonsense, but it also implies an attempt to mislead or swindle.
Examples of use:
"I don’t know much about history, and I wouldn’t give a nickel for all the history in the world. It means nothing to me. History is more or less bunk."--Henry Ford, 1916
"Huh! That fad diet? It's a bunch of bunkum."