How many endangered(EN) species are there in India as per the IUCN Red list?
out of that how many species information we have in efloraofIndia?

Not only endangered, endemic species also have more importance, being an young energetic botanist … should help to find answers to this query others will also assist.

it is easy to search on IUCN website, how many are threatened in India.
How many are endemic to India, there is no single book to confirm.

A very exhaustive list here
List of endemic and threatened plants of India – Wikipedia

The list on Wikipedia is incorrect for sure, but its ok to start with it. Something is better than nothing.

IUCN List is not static, it is dynamic with species being added, deleted or shifted from one category to another category.

In 2017 I tried to analyse based on the IUCN list for India in 2017-I.
It is available on the separate page in eFI under the heading “Endemic/Threatened Flora of India”, the secon last heading on right side panel:
Since then IUCN list must have changed considerably; so is the species in eFI. So the information available need to be updated now.
It is time consuming exercise.

List of Endemic vascular plant species of India is available in the book published by BSI. About the book-

Thank you very much respected experts for your response, I will go through your suggestions,