nofollow is an attribute that is used on links (both internal and external) to tell the search engines not to follow that link. sites mostly use nofollow attribute to cut down spam and not to pass PR to the external links (which in turn cut down spam as well)
In layman's term, it cannot contribute any juice to your ranking. Although, it can help drive more traffic to your site.
Nofollow is a link attribute that allows website owners to tell search engines that a particular link does not confer credit to the target site. This is done to avoid unwanted links or spam links because there are websites that get spam links on them....
Yep no follow tells search engines not to follow the link and it does mean pr juice is not given to that site which is linked.
Nofollow" provides a way for webmasters to tell search engines "Don't follow links on this page" or "Don't follow this specific link.
NoFollow could also help advertise your website even it doesn't have any attribute to the PR link juice.