1) It means “with”. In practice, the word participates in the legal term “Cum testamento annexo”, which means “with the will annexed”. It is used in the area of Wills & Probates, where details a left personal will with no detailed executor’s name. Or alternatively, the detailed in the will executor has died already, or does not wish to act as executor, etc. The word relates also to the legal expression “cum privilegio ad imprimendum solum”, which literally means “with the exclusive right to print”. Basically it explains a copyright notice.
2) It means “when”, “since” and ”although”.
Nowadays the word is used to describe a thing or a person with two roles, or that change from one condition in another.