Meaning of "pois não" in Portuguese

When in Brazil, if you are at a bar, restaurant or some other service venue, you might hear the clerk or salesperson ask in Portuguese: Pois não?The English language does not have a similar phrase and the literal translation from Portuguese wouldn't make any sense.The phrase means approximately: "Can I help you?" = Posso ajudá-lo(a)? You can also use "Posso ajudá-lo(a)?" in this context, but it's good to know both phrases.