Qalb (inversion) occurs when related elements are put in an order or relation opposite to the ordinarily expected one. Rhetorically, the reversal may sometimes be tolerable because it produces a subtle appropriateness or emphatic effect; not every reversal is good style.
«عَرَضْتُ النَّاقَةَ عَلَى الْحَوْضِ»
I brought the she-camel before the watering trough.
The intended event is getting the animal to the water. The construction may present the conventional relation from an unexpected direction, which the source discusses under qalb.
Qalb differs from simple fronting or postponement: ordinary word-order changes may leave the semantic relations intact, while qalb also reverses the expected presentation of those relations.