A plain-language explanation
Noindex is a directive for search engine robots stating that a specific page should not appear in search results.
Where it helps in practice
Noindex asks a search engine to exclude a page after reading it, so blocking crawling may prevent the directive from being seen.
The decision before implementation
Review page value, internal links, canonical and whether exclusion is temporary or permanent.
How to verify the result
Monitor URL inspection, crawl logs, sitemaps and accidental reappearance after template changes.