Neither laka nor shaʾnu is itself a verb; one is a prepositional phrase, the other a noun.
The author calls the construction “verbal in meaning” because it conveys something like What are you doing? despite having no overt finite verb.
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What “Verb in Meaning” Actually Means
Al-Mafʿūl Maʿahu: Accompaniment and Coordination
Neither laka nor shaʾnu is itself a verb; one is a prepositional phrase, the other a noun.
The author calls the construction “verbal in meaning” because it conveys something like What are you doing? despite having no overt finite verb.