Listen to this video carefully:

https://www.youtube.com/watch?v=8aGhZQkoFbQ

Hello Ganesan,
Please check out the below link maybe it will help you.
https://www.geeksforgeeks.org/synchronous-and-asynchronous-in-javascript/
https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Asynchronous/Introducing