Extroverted sevens are talkative sociable, fast paced and fun loving. They usually have a large variety of friends and experiences.
Sensing sevens are action oriented, playful and realistic. They learn from first hand experiences and observation.
Feeling sevens tend to be gentler more sympathetic and more people orientated
Irrational are very open and have difficulty seeing projects to the end
The best way to form a rough understanding, to me, is to look at the traits of the Enneatype and the MBTI type and mash them together. Some of them will contropose one another, others will corroborate, and still others will just be orthogonal. Others' descriptions might give you a starting point.