plants can be either:
Monecious (spp?) : Mono= "one home" for both sex parts.

Dioecious: Di= "2 [different] homes" for each sex part.

So with a dioecious plant, you can have a "purely female" plant, having only flowers. Our people smoke the "flower" so thats why we keep the female and ditch the male.
LIP is right, "sexing" just means forcing the plant into "flower mode" so you can determine the sex.
peace