This is a Counter64 that counts how many packets have matched this specific packet filter, incrementing each time a packet hits the rule (per its own description). Because it only increments while the paired counter-status object is enabled, an admin uses it to confirm a filter is actually being exercised by real traffic rather than sitting unused, which is invaluable when troubleshooting a suspected dead ACL entry. For example, an admin on VI 4 facing the Frame Relay uplink who just tightened a deny rule would poll this counter to see it climb from zero as blocked packets start arriving.