It's fairly easy concept to understand. You write original articles (Hubs). As you publish hubs, answer questions, participate in discussions and comment on other Hubs, your personal score increases.
Google Adsense ads are displayed on your Hubs (articles). You receive a percentage of the advertising dollars made from the clicks on these ads.
Therefore, the more Hubs (articles) you write, the larger the number of Google Adsense ads that are displayed, the larger the chance of making passive income. You must be a member of Google Adsense to participate in this feature. Check the "Earnings" section of your account for set up guidance.