I am new to api.ai. I want to send data to the web server and receive it and then give it to the users? From the documentation that I read, I understood that I have to use a webhook. But I am not sure how will api.ai send and receive the data?
Can the webhook be developed in any language?
The webhook is a web service that you implement in any language and on any platform, with an HTTP (must be https for ghome) and JSON interface, that fullfils (in their lingo) a user intent.
API.AI matches a user utterance to an intent (which then suggests entity values and a response) and they pass these in the call to your web service. You do whatever processing you need - your domain logic - and then return a speech response for the user and optionally some API.AI contexts.
You can read more about it (and about slot filling fulfillment which is a little different) here.