In the first gamebook, there are two characteristics: Skill and Heath. Each one is counted in "points". They cannot get below zero, so you can only have 0 or more Skill points and 0 or more Health points.
Skill is used in fights, but also in the adventure when it comes to do a special move like climbing, jumping, flying or swimming. The more Skills a dragon or a character has, the easier fights and the more choices.
Health shows the physical status of your character. If it reaches 0, then your character dies, meaning your adventure is over. Health is used in fights, and when a strong effort has to be made during your quest. An injury, in a fight or in your adventure, will take away some of your Health points, so avoid fights if your Health level is low.