ip verify unicast reverse-path command is used, the feature checks to determine whether any packet received at the router interface arrives on one of the best return paths to the source of the packet. It checks this be examining the source IP address, comparing it to the routing table, and making sure that the interface it came in on matches with the interface associated with the source address in the routing table. If this is the case, the packet will be accepted and routed correctly. In such a case, the access list created in the above configuration actually does nothing.
However, if the source IP address fails this check, that is, if the source IP should not be seen on the interface the packet came in on, it will be dropped unless there is an ACL specified in the command. If there is, and the source IP address matches that in the ACL permit statement, then the check is bypassed. What this means is that the packet is successfully routed.
Note however, that regardless of whether the packet is dropped or forwarded, the packet is counted in the global IP traffic statistics for uRPF drops, and in the interface statistics for uRPF.
I hope this has been helpful!