What do you mean by "backed by the hardware-based Knox platform security"?

Knox Workspace leverages and extends the security features of the underlying Knox platform, which is built into Samsung smartphones, tablets, and other devices.

The Knox platform leverages a "completely isolated" hardware region called TrustZone where cryptographic keys are stored, and this area is completely impervious to attack and inaccessible. That's what Samsung means by "hardware-based" security.

If the device is ever compromised, Knox Workspace is permanently locked because the encryption key for Workspace will never be retrievable from the HW chipset where the key has been stored. Data inside Knox Workspace becomes completely inaccessible, and enterprises keep their important data from being lost or stolen.