Your character has four attributes: strength, dexterity, intelligence, and charisma. They are rated from d4 to d12. This is the die you roll when you attempt a challenge related to that attribute. For example, if you wanted to jump across a pit, you would roll your strength die, as that attribute governs athletics. The narrator could also decide that dexterity is appropriate for jumping over pits, too.
Strength is the measure of a character's physical might and athleticism as well as their durability and stamina. It's important for melee weapons as well as resisting damage.
Dexterity includes hand-eye coordination, balance, reflexes, and agility. It's important for ranged weapons, initiative, and avoiding attacks.
Intelligence covers everything from reason and memory to perception and willpower. It's important for healing, repairing, initiative, and researching adventures.
Charisma determines how well a character is able to deceive, intimidate, persuade, or seduce others. It's important for rallying your team, taunting or misdirecting enemies, and negotiating with others.
You begin with one attribute at d8, one at d6, and two at d4. After completing an adventure, you may raise one attribute by a die value, up to a maximum of d12.