"pts" is short for "points", whereas 1 pt is 1/8 inches away from the racket's middle. A head light balance means the balance is near the butt (the handle), while a head heavy balance means the balance is near the racket head. So 2 pts HL means the balance point is 1/4 inches away from the middle of the racket, towards the butt. 12HH means the balance point is 1.5 inches away from the middle, towards the racket head.
Sometimes you see 32.5cm in the field of balance point on a racket, instead of how many pts HL/HH. That length is measured from the butt (bottom of the handle). A standard racket is 27 inches long, i.e. 68.6cm. The middle is at 34.3cm. The distance between the middle of the racket, and its balance point (centre of gravity or "weight centre") is 34.3-32.5 = 1.8cm. 1.8 cm is 0.7087 inches, which when divided by 0.125 (which is 1/8) is roughly 5.7. Therefore it's 5.7 pts head light.
But you have to be aware of the fact that there's a "strung balance" and an "unstrung balance". Like "strung weight" and "unstrung weight", the racket's balance changes when there's strings in the racket head, usually 3-4 pts less head light (or more head heavy, which is the same thing) and 15-20 grams heavier than when the racket is unstrung.
A 12 pt HL racket has a balance point much nearer to the butt cap of the handle than a 2 pt HL racket, whereas a 12 pt HH racket has a balance very near to the top of the racket head.
The more head light a racket is, the more maneuverable the racket is. But the more head heavy the racket is, the more powerful it is. So you see most "beginner's racket" has a HH balance because beginners need power (which some disagree), and a tour level racket has a much HL balance.