Network Address Translation (NAT) is used when you want your real servers to access the outside network. When using NAT, all packets will appear as though they came from the Array appliance. Setting up NAT in CLI:
nat port <vip> <network_ip> <netmask> [timeout]

example: (config)#nat port 10.10.0.2 192.168.10.0 255.255.255.0 60

Webui Array OS 6.4 or later:
Under "System Configuration" ->Advanced Networking->"NAT" tab -> "Add NAT Port"