TBW stands for terabytes written, which represents the lifespan of a SSD.
The lifespan is determined by how much data can be written to the SSD (i.e. data storage).
The TBW represents the total write endurance of a SSD throughout its lifespan.
For instance, 72TBW means 72TB of data can be written, which equals writing 50GB daily for four years.

(72TB = 72,000GB= 4 years X 365 days X approximately 50GB)