The term Jewish left describes Jews who identify with or support left wing or liberal causes. There is no one organization or movement which constitutes the "Jewish left".
Well-known Jewish writers who describe themselves as politically and socially left-wing include include Michael Lerner, Noam Chomsky, Howard Zinn, and Arthur Waskow.
There is no set relationship between the political and religious beliefs of Jews; one can be politically left, while at the same time religiously conservative (and vice-versa.) At the same time, it has been noted by a number of writers that most of the Jewish left is religiously liberal or secular.