Nofollow (rel=“nofollow”) is a link attribute that instructs search engine crawlers not to follow the link and thus not to crawl the linked page.
If you notice the issue "Nofollow in HTML and HTTP header" in your site audit report, this refers to Pages found with a nofollow directive implemented both in meta tag and in HTTP response header (X-Robots tag).
It is enough to implement a "nofollow" either in HTML meta tag or in HTTP header. So to solve this issue, pick only the meta tag method, or the HTTP header method to implement the nofollow directive.