A male ferret is called a Hob and a female is a  Jill. Both sexes are suitable as pets.
The male can be two and a half times the size of the female.
The hob has an odour if in season and castration removes the odour and any sexual urges . Castration also allows Hobs (both castrated) to be housed together with no fear of fighting ,or to be housed with Jills.
A Jill ferret can have problems if left in season unmated. One such problem is a type of  anaemia that can have fatal consequences.
The solutions are:
a) to mate her and raise a litter.*
b) to mate her to a Hob that has had a vasectomy, producing no litter.
c) A hormone injection administered by a vet, this will need doing each year.
d) Spaying, an operation performed by a vet, the ferret cannot be used for breeding  subsequently .This is the permanent solution.

* Don’t raise litters of ferrets unless you are certain you can find good homes for the offspring, there can be as many as 12 kit’s (babies).