I want to know what feature nbu supprt when destination is cloud . suc as compression, encyption, deduplication etc
Refer to this section in the NBU Cloud Admin manual:
About data encryption for cloud storage
You will see in this section that KMS encryption is used for cloud storage.
Client-based encryption in the policy is covered in See the NetBackup Security and Encryption Guide:
You will see that it requires configuration on each client individually.
You can also read up about different security models in Chapter 2 of the Security and Encryption Guide.