A word that tells your dog they are free to move out of a position you asked them to hold. Common release cues are "Okay!", "Break!", or "Free!".
A release cue is the bookend to any stay. When your dog learns that a sit, down, or stay only ends when they hear the release word, they hold the position until you say so, rather than deciding for themselves when they are done.
To build one, pick a word you do not use much in everyday conversation, then say it and immediately encourage your dog to move, luring them out of position with a treat or a bit of play if needed. With practice, the word itself comes to mean "you are free to go."
Always release your dog on purpose. If you let them wander off on their own, you teach them that they can self-release, which weakens every stay you train.