Noindex by Path

After installation you can find “Noindex by path” option in the main menu. This allows you to simply add relative paths
you need to exclude from SERPs. Add a path (including slashes from begging and the end of the string) and save the
changes. Since this plugin is called to be “simple” you can add only one path at once, but the process is smooth
and easy.

Plugin will add “noindex” meta tag which is an instruction for search engines that this particular page should not be indexed.
Technically it modifies wp_head tag.