Once a person makes a purchase (signs up, performs some sort of other action - depends on the goal of the company), the product (service) provider sees that the now-new customer came to the site via using the specific affiliate link. In turn, the affiliate gets a certain share of the revenue (this amount is usually agreed upon before getting the affiliate link).
This doesn’t mean you need to be William Shakespeare. In fact, it’s better if you don’t write in a fancy convoluted way. Writing in a simple voice is ideal. Write in a way that is easy to understand. Not an attempt to show off.

It also shows you the related searches, auto-complete phrases, and the "people also asked for" section, which reveals topics related to your main keyword phrase. You can use Google to your advantage by running your target keywords to see the type of content that is available. This will help you narrow your sights to a topic that's got a high search volume and low competition.
Out of all these options though, blogging is arguably the most effective one and the one that has the best chances of success early on – plus, literally anyone can start a blog and almost anyone can be successful, but only if they’re willing to put in the time and work.