I'll assume you are joking or maybe ignorant but 'cum' pronounced as [koom] is used in this context as a preposition. It means combined with or describing a thing with dual nature or function.
Thus 'vice-president cum co-founder' means that the person was the vice-president as well as co-founder.
It is vastly different from the vulgar slang 'cum' which means have an orgasm [verb] or semen [noun].
Too much green will rot your brain, dude. Go expand your reading materials.
