"Really, you shouldn't accuse... dangerous thing to say... wands away, please!"
-- Madam Malkin, trying to defuse a sticky situation between Harry and Narcissa (HBP6)
Common way of saying “Put your wands away,” meaning “No magic allowed.” The phrase, when spoken by a teacher at Hogwarts, means that the upcoming lesson will be a theory lesson without any actual magic practice. The students are never particularly excited to hear that order at the beginning of a lesson:
Many of the class exchanged gloomy looks; the order ‘wands away’ had never yet been followed by a lesson they had found interesting. Harry shoved his wand back inside his bag and pulled out quill, ink and parchment (OP12).