These values depend on how strong or weak your character is. Nearly everything is represented by stats, even how pretty your character is. In many cases, they determine how your character should RP (are they frail, nimble, clever, gruff, etc). The seven primary stats are:
Life: Which is how long you can keep on ticking. This can be the equivalent of hit points on most roleplaying games.
Endurance: Can you take a punch? How much can you before getting winded, or hurt?
Strength: Shows if your character is THAT strong. Weight lifters would have a high STR.
Dexterity: Three words sum it all up: Hand-eye coordination. Or foot-eye coordination. Or the coordination of any other body part.
Intelligence: Does he know what he is doing, or is he stupid and just goes around doing whatever he feels like? Basically how much common sense he has and how smart they are. How fast he learns, how much he knows, how easy he understands things.
Spirituality: How much inner balance do you have. The truly enlightened. Is your inner spirit in check? Are you strong in mind? Are you attuned to the spiritual world around you?
Charisma: This shows if you are a leader or a follower. It is also associated with how much influence you can have on someone. The influence can be positive or negative: you can charm someone with charisma, but you can also intimidate them.
These seven stats are the ones you can spend XP to raise directly. There are seven more derived stats which often serve as big a role:
Health: The average of Life and Endurance. Basically its how healthy you are, or resistant to disease and illness.
Constitution: Average of Endurance and Strength. Stamina and how big a person is. The ability to exert themselves for long periods. Simple.
Agility: Average of Strength and Dexterity. How flimsy is your character? Can they coordinate their body while exerting it to its fullest? Used for jumping, running, and such.
Finesse: Average of Dexterity and Intelligence. How quickly can your character react to a sudden change, like rocks falling from overhead?
Awareness: Average of Spirituality and Intelligence. Do they notice everything that's going on around them?
Presence: Average of Charisma and Spirituality. How much are they there? Does he turn heads?
Appearance: Average of Life and Charisma. Do they appear exceedingly beautiful or do they appear ugly if they aren't trying (or deliberately failing)? Are they average?
To raise a stat or skill costs XP, as you might expect. How much XP it costs is tied to how high the stat already is: the higher it is currently, the more XP it will take to raise it even higher.
To raise a stat costs 10% of their value, rounded down. For instance, when your INT is at 20, it takes 2 XP to raise it to 21. It will stay that 2:1 ratio until you get it to 30, when it becomes 3:1, and so on.
Skills, on the other hand, are cheaper to raise. Raising a skill costs 7.5% of its current level, rounded down. So if your skill is at 10, then it takes .75 xp to raise it to 11. The only exception is when you're raising a skill from 0-10, which also costs .75 XP per point.