Since there are only 40 HCPs in a pack of cards, a 12+ HCP hand, shows a better than average hand with the opener

HCP can be enhanced with some extras as distribution points: 

Trump auction

• 3 points if you have VOID (no card of a suit hence can be ruffed)
• 2 point if you have a Singleton
• 1 point for a doubleton
• 1 point if responder finds a Suit fit.

No Trump auction

• 1 point for every extra card over 4 for length.