Hello Crescellia Yu Thanks for this great question.
Web monetization is like these:
From the creator's(someone providing a content online) angle:
It's a service or a system that allows you get money directly from the people using your contents. In this case, you're getting direct revenue(money) in real time because a user out there is using the content you're providing. This content could be a blog post, a website, a game, a video, a podcast. Anything at all. If it can be on a url, it can be web monetized.
From the user's (The person using a content) angle: It's a system or a service that allows you pay or tip the creator of the content you're using in real time, immediately you're using the content, you're supporting the creator...
Now the advantage in this is that, the creator can decide that, Ohh, if any user that uses web monetization comes to my blog, let them get an extra information apart from the public blog post, Ohhh, my website/blog will not show ads when a user using web monetization is using it, I need to make their experience better. Ohh perhaps if a user using web monetization comes to my game, give them an extra life, or a golden sword, or an extra stage.
Web monetization can be explained in different ways, depending on which angle you're explaining from.
I'd be glad to answer more questions.
My friend Chris Lawrence from Grant for the Web can also add to this.