There are lots of different ways to earn money from YouTube.
The main income will come from the YouTube partner program. You will get a share of the revenue YouTube generates from the ads that they place on the videos you upload. There is certain conditions you must meet to get accepted into the partner program. You need to have a strong volume of views coming in everyday and you need to have lots of active subscribers.
There are also ways to earn money from YouTube by selling affiliate products to your viewers. To Learn how to make money as an affiliate check out this nice blog about making money online Make Money With YouTube - Elitecashmoney.com