This blog post explains what the figures from SEOmoz mean and how you can best interpret and apply them to your own competition analysis: http://swissmademarketing.com/practical-application-of- competition-data/
Juice Links are Links, which will count towards your rankings. Eg. these types of links would be excluded from Juice Links:
SEOmoz provide more information here: http://apiwiki.seomoz.org/w/page/13991139/Juice-Passing