Hello Jackelyn Jordan!
That's a great question! The way we make money on HubPages is through the several Affiliate Advertising Programs including Google AdSense, HubPages Ad Program, eBay and Amazon Affiliates Programs. You have to apply and be accepted into each program (starting with Google AdSense first) and then you can earn from the Ads placed in your Hubs. To learn more about the different programs and how to sign-up for them as well as how to use them for targeted audiences, check out this article: http://hubpages.com/t/2ddcd1
I hope this helps! Good luck!