The question "How many is several?" illustrates which function of language?

The question "How many is several?" showcases the metalingual function of language. The metalingual function occurs when language is used to discuss or clarify itself, focusing on the code or system being used to communicate. In this instance, the speaker is seeking clarification on the term "several," which requires an exploration of the meaning and usage of that particular word. This focus on language itself—its definitions, interpretations, and contexts—demonstrates the essence of the metalingual function in communication.

Other functions, such as descriptive, conative, and expressive, are oriented towards conveying information, persuading the listener, or expressing emotions, respectively, rather than examining the language's structure or meanings.