There are several ways that you can make money through Hubpages. The simplest of them is to signup for a free google adsense account and use your publisher id from there in your Hubpages settings. Basically what this means is that when an ad appears on your page, it is linked to your Google account, and if somebody clicks on that ad, you earn money from it.

You can also write pages on topics that you know a lot about for money. There are people out there willing to pay for excellent content and writing on many different topics, and you could use this avenue for earning revenue. 

There are a lot more complicated methods of making money from Hubpages which involve linking strategies to other websites for affiliate income, but this is very involved and requires specialist training.

The best place to start is to have a look at what people are searching for in something like Google Trends or Yahoo Answers and see if there is anything that you have knowledge in that you could write a page about. The old saying of "If you build it, they will come" is quite true on the interent. If you write/build a page that people find interesting, you are bound to find many different ways of "monetizing" your content.