What is the meaning of Ibn Malik's (may Allah have mercy on him) statement, "And the matching one is ifa'lan..."?

The student: His statement: ifa'lan?

The Shaykh : What?
The student: His statement: "And the matching one"

The Shaykh : Yes.
The student: Is the intended meaning the one matching the previous meter, ifa'lan? Or the one matching the second meter?

The Shaykh : Iqa'anss, the one matching it in meter, iqa'anss.
The student: Matching its meter?

The Shaykh : Its meter, yes, ifa'lan, the one matching it is ifa'lan.
The student: The past and the present?

The Shaykh : Which one?
The student: ...

The Shaykh : Huh?
The student: ...

The Shaykh : How?
The student: Does the past and the present come from it?

The Shaykh : Yes, indeed.