Figma is mostly used for website and app prototyping. It's very popular because it allows for multi-user collaboration, like a Google doc. Older prototyping tools like Invision or Sketch did not have this, and it was a major differentiator.

You can create different screens and set up click points, such as a button. Clicking the button navigates you to another screen in your design. This is called "interactive prototyping".

Figma puts these interactive prototypes on the web, so designers can create a visual prototype that can be tested on mobile and desktop devices. It's more realistic than simply looking at pictures of mockups. The biggest advantage is that it does not require developers to write working code and deploy a whole app just to click around and test it out.