Edited because, after reading his explanation, it makes more sense.
HCN = 14 total electrons, 8 of which are involved in the sigma and pi bonds, therefore, 6 are unbonded electrons. (Core electrons + the 2 valence electrons (lone pair) on the Nitrogen.)
VERY odd way of asking that question.
I have uploaded the attachment of his explanation in case you didn't have that at your disposal. Good luck with your studying!