The number of packets that are allowed by each line of an access-list is displayed as the number of matches. "Check" indicates how many times a packet was compared to an access-list command line but failed to match.
Example from one of Cisco's command references covering the "show access-lists" command:
Router# show access-lists 101
Extended IP access list 101
permit tcp host 198.92.32.130 any established (4304 matches) check=5
permit udp host 198.92.32.130 any eq domain (129 matches)
permit icmp host 198.92.32.130 any
permit tcp host 198.92.32.130 host 171.69.2.141 gt 1023
permit tcp host 198.92.32.130 host 171.69.2.135 eq smtp (2 matches)
permit tcp host 198.92.32.130 host 198.92.30.32 eq smtp
permit tcp host 198.92.32.130 host 171.69.108.33 eq smtp
permit udp host 198.92.32.130 host 171.68.225.190 eq syslog
permit udp host 198.92.32.130 host 171.68.225.126 eq syslog
deny ip 150.136.0.0 0.0.255.255 224.0.0.0 15.255.255.255
deny ip 171.68.0.0 0.1.255.255 224.0.0.0 15.255.255.255 (2 matches) check=1
deny ip 172.24.24.0 0.0.1.255 224.0.0.0 15.255.255.255
deny ip 192.82.152.0 0.0.0.255 224.0.0.0 15.255.255.255
deny ip 192.122.173.0 0.0.0.255 224.0.0.0 15.255.255.255
deny ip 192.122.174.0 0.0.0.255 224.0.0.0 15.255.255.255
deny ip 192.135.239.0 0.0.0.255 224.0.0.0 15.255.255.255
deny ip 192.135.240.0 0.0.7.255 224.0.0.0 15.255.255.255
deny ip 192.135.248.0 0.0.3.255 224.0.0.0 15.255.255.255
The high number of checks but no matches for the "deny" command line in your access-list 12 indicates that the rule was checked 177521 times, and the source IP address in those packets was never one of the 2048 possible addresses between 10.48.0.0 and 10.48.7.255, inclusive.
