Great!
Kanuwa will explain that casting is based on energy, which is continuous and not discrete. Energy is gained passively from existing, and also from meditation, and also from doing things related to your Way or your precepts. So, an Open practitioner whose precepts were about knowledge would gain energy from learning, a Flowers practitioner whose precepts were about sensation would gain energy from sensation, etc. Each person has a maximum amount of energy that they can store — it's almost always more than what they could generate in a day.
Rituals are the most basal and most common type of casting. Rituals involve trappings, or components that are used to make the energy do what you want. These include words, movements, times, places, ingredients, and tools. Spells are a compressed version of rituals that are typically way less efficient, but let you dispense with many of the trappings. Typically, they are also shorter. Most rituals have spell versions and vice versa.
Rituals and spells typically cause instantaneous or limited duration effects. It's possible to place an effect that is self sustaining, or has a very long duration. These are called enchantments, for people — though this is ambiguous between mind affecting effects, so there's been a movement to rename them to something else like 'augmentation' — artifice for portable objects, and consecrations for places and buildings. Kanuwa doesn't know how to cast any of them, though. He only knows spells and rituals.
He stops himself from talking about the effects each Way can cause, because they're on the street the soup kitchen is at and they're almost there.