The technical name for a cat spay is an ovarohysterectomy, which means the removal of the ovaries and uterus. You will, more commonly, hear people saying that their cat has been spayed or dressed.
The operation is a one off procedure and is not reversible. Once your cat has been spayed she will never be able to have kitten
Spaying lowers the risk of contracting Feline Leukaemia Virus, Immunodeficiency Virus and Infectious Peritonitis Virus. All of theses fatal diseases are believe to be spread, in part, by mating as well as through close contact e.g. fighting. Spayed cats are not mated and generally have less contact with other cats in the neighbourhood and therefore their risk of infection is decreased.