The fuel maps are correction values. They can be displayed in a number of real world values, but to keep it simple, we leave them as a raw number where up = more fuel and down = less fuel.
Load it calculated by an equation, not a singular measurable event. Injection ms represents the closest real world thing you can measure and the more load on the engine, the higher up the "load" scale you will be at the given RPM. The number in that cell is used to adjust fuel from the theoretically calculated amount into the real world needed amount.