The golden cumpas...explanation ?

okay so that movie the golden cumpas...with the girl who can read the alethiometer ...w/e ...so yaa, i honestly love that movie but at the same time i dont understand it at all...can someone explain what the hell the whole "dust" thing is about...and all that ****..cuz im soo confused and i've seen the movie like...more than 5 times..but still dont get it...soo yaaa, plz n thx :) !!♥