If the description is a noun, they make the noun the subject; whether it comes later or earlier, and the predicate is the description, why?

The Shaykh : I say: If the description is a noun, they make the noun the subject, whether it comes later or earlier, and the predicate is the description. Why? Because the subject is the one about whom a judgment is made, and the predicate, in meaning, is a description of the subject. "Zayd is standing"; his description is standing, but standing is not a description of Zayd.
The student: What does that mean?

The Shaykh : Yes? Ibn Dawud.
The student: Shaykh, may Allah reward you with good, O Shaykh. We said: If it is not sufficient in other cases, then the interrogative is dispensed with. Then we also gave an example, O Shaykh, —not that it was my intention—