Hi Karthik ,
https://video.mendix.com/watch/RMw45uwCAjYi2ej7ykAseu
The above video might help you to consume the rest service.
Consume Rest Service helps us to consume the API which has been defined by anyother system.
With the help of this service , we will be able to get the data from the other system in to our mendix app easily.
I suggest to take this learning path.
https://academy.mendix.com/link/modules/138/lectures/1226/5.1-Consume-a-REST-Service
If you still need more after this, you could a tend one of our trainer led $ courses