A conventional way of showing a two- suited hand after a weak opposing bid. A jump in a minor that shows the minor bid and the unbid major.
West’s 4♣ shows at least five clubs and at least five spades. East usually corrects to 4♠ or raises to 5♣. West might hold:
Playing Leaping Michaels, a cue bid of the suit opened (3♥ in this example) would ask for a stopper rather than denote a two-suited hand.