Commentators unanimously interpret this verse as a prophecy about the Messiah's kingdom. God promises to take a humble 'twig' (Jesus, from the line of David) and plant it on a 'high mountain' (the spiritual center of His rule, Zion). This twig will grow supernaturally into a magnificent 'cedar,' symbolizing the incredible growth of Christ's kingdom from a small beginning to a glorious, worldwide reality.