Hi,

I am seeing a lot of URLs of my websites are appearing within GSC under coverage in the What is Discovered - currently not indexed tab, I don't know how to index these URLs as these URLs are important for my websites. please suggest me solution to this issue.

Try to change your content as Google is seeing your content similar to old pages this is why it is not indexing these pages.

This is because the URL found might be canonical and Google have decided not to index but you can manually request for indexing.