Posted Today, 11:07
It asks for the queen of trumps - here, spades. Several different response schemes exist. 5♠ denies the queen, higher bids show it. But which exact higher bid to use depends on agreements. A common agreement is to immediately also answer with the queen as if partner asked for kings.
P.S. I wrote this under the assumption that 4NT was RKC Blackwood for spades, but this seems to be false. Sorry.