It means that operations don't get executed in the same order on every replica. If the systems state depends on the ordering of operations, then each replica might be in a different state for the same set of operations.
"Consistent replication" would be using a protocol like Paxos to have the replicas decide on a single order of operations.
"Consistent replication" would be using a protocol like Paxos to have the replicas decide on a single order of operations.