أما الواحد فيعني أن صانع العالم واحد
As for “one,” it means that the Maker of the world is one.
The argument does not stop at asserting some ultimate originator. The originator is also described as one, not as two independent Necessary Existents jointly constituting the ultimate ground of reality.
Here unity means more than counting one item; it expresses divine uniqueness. The passage connects this to the concept of necessary existence, while the fuller argumentative treatment of unity follows in the next section.