Regular cannabis seeds are bred from a male and a female parent, and can produce male or female plants. There is no way to tell whether a regular cannabis seed will produce a male or female plant apart from growing and flowering it. However, once a plant has been in the flowering phase for about two weeks, it is quite easy to tell the difference between males, with their oval pods, and females, which produce a a teardrop-shaped calyx from which a pair of white hairs emerge.
When growing regular cannabis seeds, the natural ratio of females to males is around one-to-one (66% female). When planning a grow, it is best to assume that half of the seeds started will turn out female and germinate extra seeds to account for the males that will be discarded early in flowering.