Complex sentence: The "flex-office" design is an open-plan layout where employees do not have their own personal workstation, but rather, share workstations with co-workers, this is commonly referred to as hot desking.
Split into simpler sentences: The "flex-office" design is an open-plan layout where employees do not have their own personal workstation. Workstations are shared with co-workers, and this is commonly referred to as hot desking.