Google assistant is currently available in Chinese, Dutch, Danish, English, French, German, Indonesian, Japanese, Italian, Korean, Norwegian, Portuguese (Brazil) ,Russian Spanish and Hindi. As India is one of the major smart phone user, Google is always try to encash it by adding special features to help Indians. But majority of the Indians are speaking Hindi than English. So Google came up with the idea of adding Hindi in Google assistant.
It is in trial basis only. Google assistant will understand some words only. It is not fully equipped to support Hindi language. It can understand and responds to some of the simple sentences like Bharat ki Rajdhani kya hai, AAj ka mausam kaisa hai, Kichdi kaise banate hai ... But the work is going on to fully implement the Hindi language support in Google assistant.
If you want to change the language for Google assistant do the following. but once you changed the language for input in your phone, your phone will use the changed language only in all its apps.
1.On your Android phone or tablet, touch and hold the Home button or say hello Google.
2. At the bottom right corner tap the 3 small lines written as more
3.It will take you to Google home. Where you touch settings.
4.Again you tap the settings
5. And in settings tap assistant
6. And in assistant tap languages.
7. lastly tap add languages. You can add Hindi there.