If you create quality content, establish your niche, and grow your audience, it can be rather easy to make money off Youtube Monetization. Once you check off all the boxes necessary for monetization, Youtube will start putting ads in front of your videos. You get paid a set amount of money based on how many people watch the ads all the way through (or if they watch past 30 seconds).
Therefore, if you have thousands, or millions of viewers, you'll be able to make lots of cash off Youtube monetization. Advertising your channel on other social media platforms is also helpful in growing your audience - Instagram and Tumblr have millions of users, and if you use the right hashtags, you can grow a large following.