I've got one project which has a storybook by default installed.
I want to ask that anybody please explain to me what is the use of a storybook and how to use that. , What are the benefits of this module in our app? I don't understand this concept.
Storybook is a tool, and you can use it in different ways.
Some teams use it as a form of "visual unit test" for UI components. For every component, they create a story with a lot of variations (eg. in React, lots of different props), similar to how you'd write unit tests to cover variations in how a function is called. In fact, the tool even has its own integration with Jest/Playwright for checking all those component variations as tests.
Other teams instead use it more to showcase components, so their teammates have a nicely documented library of re-usable widgets (each with their own story). In that case, it's basically just a way to document your own components, visually.
Ultimately, how you use it is up to your team. As their official site says:
Storybook is a frontend workshop for building UI components and pages in isolation. Thousands of teams use it for UI development, testing, and documentation. It's open source and free.