Google search employee John Mueller explained that the "nofollow" attribute should not be considered an alternative to the "noindex" attribute. Nofollow will not help avoid indexing pages because Google can find and index links closed with this attribute.
Quite literally, Mueller said, "Essentially, nofollow tells us that we shouldn't pass PageRank to these pages. But that doesn't mean we won't index them. So if you want to disallow indexing a page, add noindex to it."
That is to be understood as follows: noindex is a directive for the search engine. And nofollow is a search engine cue.