Attributes
There are 9(!) primary attributes:
Strength, Quickness, Dexterity, Constitution, Health, Charisma, Intelligence, Willpower and Astral.
Soon the players came up with Perception as you need something to test against if you can notice when someone wants to throw a garrote around your neck from behind. Later this stat was canonised so all in all this is 10 primary attribute.
Health isn't HP tho HP is depending on Health. This stat is also for the general resistance to deseases, poisons, spoiled foods etc.
Astral is emotional stability, someone with low Astral can be angered faster for example. Also in the world of MAGUS beside the Physical Body living things have Mental Body (tied to Intelligence) and Astral Body. These exist in different Planes and can be perceived by those who trained so or have the ability. The Astral Plain is also the world of dreams.
Most of the time a human PC has these between 3-18. The maximum is 20.
Their value above 10 is tasted with d10 when necessary. (Example: if a PC has Qck. Dex. and Per. 18 and wishes to catch an arrow flying toward him I'll have the player test Perception if he can notice it, then Qickness if he was fast enough then Dexterity if he was skillful enough to cath it, all with d10 against 8, so he needs to roll <= 8 three times).

There are a few drivatives or secondary attributes.
Health Points, Pain Points (if you get hit these start to get lower first), Initiative Value, Attacking Value, Defending Value, Targeting Value - these are all important for battles. Then there's the Mana Points (Bards, Witches, Witchmasters, Firemages, Wizards) and Grace Points (Clerics, Paladins) for magic. Then Psy Points. This is also "magic", more later. For raising skills one needs Skill Points of course, a derivative of Intelligence.
Also there's number of attacks per round, damage bonus, the stats of weapons and armors to modify the Fighting Values and the damage. If yuo like math then this game is for you.

In picrel you can see how attributes are rolled by the classes of the Fighter main class (Fighter, Gladiator, Headhunter, Knight) on character creation.
For example the Strength of a Fighter is decided by k6 (d6) and added to 12. So the minimum Strength a Fighter can have is 13, the max is 18. His Health is d10 + 10 (min 11, max 20).
Lots of players prefer a point allocation system for creating characters over this, in the freshest book that is the default option.