This INTEGER reports how many dedicated IPsec-offload network interface cards are installed in the gateway, per 'IPsec NIC: Number of IPsec NIC's.' It's the hardware inventory count that everything else in this NIC-specific table (downloaded SAs, encrypted/decrypted bytes) is scoped against, so an admin checking VPN throughput capacity starts here to know how many offload paths exist. A value of 0 on a gateway expected to have hardware VPN acceleration would immediately explain why VPN traffic is being handled entirely by the CPU instead.