What to do if the ads are not working

He's running some ads and he's not getting any sales. And to that I reply, welcome, sir, to the club. And so I don't really understand the question. It says is it only sales conversion that count? Or should I check for some other stats? I'm not getting sales as you can probably guess. 

Actually I do understand the question. What am I talking about? It's a perfectly normal question. So I think like in summary, what do I do? I'm running ads. I'm not getting sales. What do I do?