This signifies the Adaptive Security Virtual Appliance. It offers the same firewall, VPN, and inspection capabilities as physical ASA hardware.
In EVE-NG, you must run the /opt/unetlab/wrappers/unl_wrapper -a fixpermissions command to ensure the system can boot the image. Asav9-12-2-9.qcow2 Download
This is the specific software version (9.12.2.9). Each version contains unique bug fixes, security patches, and feature sets. This signifies the Adaptive Security Virtual Appliance