Google gives us a series of tags that we could use to educate it regarding what pages we want to be indexed, followed or not accessible.
These tags are:
Noindex: tells search engines not to include your pags in search results.
Disallow: tells them not to crawl your pages
Nofollow: tells them not to follow the links on your page.
When do you use them?
Well, we usually use them when we want to optimize the crawling budget. Imagine you have 1000 pages on the site, but 800 are actually generated by tags. You just set the tags as noindex(because it's a good practice) and now the site gets more efficiently crawled.
How do you use them? Well, with WordPress and any decent CMS, your SEO solution(Yoast, RankMath, etc) gives you options for such a task.