The grammatical name given to the construction in your question is a "wh-question". A wh-question is a type of interrogative sentence that begins with a word such as 'what', 'who', 'where', 'when', 'why', or 'how'. These words are called interrogative pronouns or adverbs because they are used to ask questions and elicit information. In this case, the wh-question word 'What' is used to inquire about the grammatical name given to a specific construction.
