The maximum number of rules per VPC is 1024.

Targets are used to specify the set of instances to which a firewall rule applies. You can target instances directly by name, or specify a VPC, VPC subnet, IP, or IP subnet, which will apply the rule to traffic going to all matching instances. Targets are additive: the rule applies to instances matching ANY target. The maximum number of targets is 256.

Filters reduce the scope of a firewall rule. Without filters, the rule applies to all packets to the targets (or from the targets, if it's an outbound rule). With multiple filters, the rule applies only to packets matching ALL filters. The maximum number of each type of filter is 256.