An indefinite noun often introduces a person or kind without a specific prior identification, while a definite form identifies something known or particular. But Arabic definiteness can also carry emphasis, prominence or a specific interpretive focus.
The discussion of ibdāl al-tankīr bi-al-taʿrīf asks how an indefinite or definite form is clarified by the intended reference. The explanation may specify which reality is intended without replacing the revealed form.
Two limits apply. First, the original definite or indefinite expression remains unchanged. Second, any more specific interpretation must be grounded in its setting. The definite article does not produce one identical rhetorical meaning in every verse.