The footnote explains that assignment of meaning (wadʿ) may arise through language, the Lawgiver, or established convention. This yields linguistic, legal-religious, and customary literal meanings.
Linguistic assignment: asad denoting a lion in Arabic.
Legal-religious assignment: salah denoting the specified ritual act in religious usage.
Customary assignment: a meaning established within general or specialized usage.
The correct reference convention matters; an expression should not be labeled figurative merely because another register uses it differently.