There are several ways to make money here. Signing up for the Hubpages Ad Program and Google AdSense are the two key ways, and using affiliates such as Amazon is another alternative.
When you publish an article here, ads show up on your article page (if the content of your article complies with Google's terms of service), readers may click on one of the ads which makes you a small profit. Profit increases with the number of clicks, yet you mustn't ever click your own ads or encourage your friends to do so. Otherwise you'll be banned - Google's eye will catch you if you try something illegal. The process must be spontaneous.
Hubpages pays you based on the number of views and Google on the number of clicks (you earn 60% of the total revenue). Clicks have different values depending on the type of ad and keywords contained in it.
You can earn through Amazon by advertising their products on your pages (you add a product link in the Amazon capsule in the submitting section), but clicks on these ads won't generate any revenue unless the visitors actually make a purchase (order their product through a link on your page). Remember that you need to sign up for this affiliate, too.
You'll get an ID or tracking code for each signup - copy and paste it into the corresponding boxes in your Hubpages account.
I suggest doing some more reading about this to get a better picture - there are many great hubs about making money on Hubpages (use the search box here on Hubpages :))
Hope this was helpful!