A:Answer It a reference to the storage capacity of the drive. In this case 2 trillion bytes expressed as 2 Terabytes.
8 bits = 1 byte
1,000 bytes = 1 Kilobyte (KB)
1,000,000 bytes = 1 Megabyte (MB)
1,000,000,000 bytes = 1 Gigabyte (GB)
1,000,000,000,000 bytes = 1 Terabyte (TB)
For more exacting details see: https://en.wikipedia.org/wiki/Hard_disk_drive