It's because they are using "read" to mean "understood/interpreted" in the sense that the reader is executing the program in their head. In their last paragrap

It's because they are using "read" to mean "understood/interpreted" in the sense that the reader is executing the program in their head. In their last paragraph: It should be so well-structured and named that its purpose and functionality are immediately apparent [when read]. This minimizes the need for others to read through **and interpret** the code, allowing them to use it more effectively. (emphasis added) So the point is really: "Good code should be so apparent that when the reader reads it they do not have to be a human interpreter."