Subdivision, or "platting" is a way to create new lots to be sold individually. For most residential properties, the minimum lot size for a standard subdivision is 7,200 square feet. So your property would need to be at least twice that (14,400 square feet) in order to get two lots. You can find more information in the Plat FAQ and Chapter 14.215 SMC.
The platting process generally follows these steps.