What is the issue?
Pages without incoming internal follow links are bad for SEO, as you do not pass strength and link equity on to your own pages, meaning it will be much more difficult for search engine bots to discover and crawl them efficiently.
How to fix
Pages without internal follow links can occur when links to the page have been removed, deleted, or set to nofollow, but the page still exists and is still in the sitemap.xml. Provide more links to the page from other thematically relevant pages on your site. If the page is no longer relevant to be ranking for users, consider deleting the page and implementing a 301 redirect to a similar URL.
Use Google Analytics data to see which pages receive the highest amount of sessions. These pages are important for your visitors, so you should incorporate these into internal linking structures and navigation elements. Learn more in this article.