Cisco ASAv is the virtualized version of Cisco's Adaptive Security Appliance (ASA) firewall.
You can now take advantage of:

High performance, scalable security
Ideal for remote worker and multi-tenant environments. Cisco ASAv delivers scalable remote access VPN, along with site-to-site, and clientless VPN options. Scales up/down for dynamic environments and high availability provides resilience.

Consistent security everywhere
Gain consistent security policies, enforcement, and protection across your environments. Provides advanced protocol inspection, including voice and video. Micro-segmentation secures east-west traffic.

Unified management
Unified management for cloud, physical, and virtual devices with Cisco Defense Orchestrator (CDO). Supports REST API, an HTTP-based interface for appliance management, security policies, status monitoring, and enables multiple cloud management solutions.

Unified security platform
Cisco SecureX, is a cloud-native, built-in platform experience within our portfolio that is integrated and open for simplicity, unified in one location for visibility, and maximizes operational efficiency.
For supported  instance types, please see the data sheet.

More solution info:
Cisco virtual firewalls for public cloud
Cisco Secure Firewall ASA Virtual (ASAv) data sheet
Cisco Secure Firewall ASA Virtual Getting Started Guide