How do you say one moment in french?

Generally : Un moment à un moment - at one moment But As a request to get time (on the phone, for example) Un moment ! or Un instant ! or une minute ! Usually you add s'il te plait or s'il vous plait (please) You can also use Deux secondes ! (Two seconds). But only with friends because it shows nervousness, impatience or exasperation that could be considered as rudeness. It sounds more like an order than a request.