Malo ovog sira, molim vas means “A little of this cheese, please” – the sentence that lets you point at one particular piece.
To show the amount, you loosely draw the size you want on a piece of paper: drawing (malen in German) and loosely give you malo. It turns out to be the wrong piece of paper, the assistant is annoyed, and you lend an ear to smooth things over – ear (Ohr in German) and waves (Wogen in German) give you ovog. Then she happily sings along with the radio: that gives you sira.
That completes your toolkit for the counter: number, weight, piece, a little, more or less.