Amazon affiliates is a referral program. You earn when someone purchases something from Amazon. So it's very different from AdSense (where you earn money from a click) or the HubPages Ad Program (where you earn money for each view).
Let's say Bob visits your Hub about Blue Widgets. He clicks on an Amazon affiliate link about Blue Widgets. While he's there, he buys something. Doesn't matter what; as long as he purchases it within 24 hours of clicking your link. You get a commission (~4% to 6%, depending on how many items you refer in a month).
Depending on what you're promoting, this can be amazingly profitable. But, before you see any results you'll need a decent level of traffic to a hub promoting Amazon products - because only a small percentage of readers will click the link, and a small percentage of them will actually purchase something.