For those who don't know what it is, here is an example scenario: You want to implement a new feature, but even the MVP will take +3 months to implement. So instead, you make a minimum UI without any business logic and when the users click on the button you tell them "coming soon" and then you test how many people wanted to interact with the feature and if it is worth it.
If nobody clicks it it doesn’t mean it’s not wanted - they may not be looking for it or understand how it would help.