Barley bread and little fish were a typical "workingman’s lunch" in Jesus’ day; they were a first century "po’ boy san’wich," if you will. Its mention into today’s gospel in a sign that the crowds who followed Jesus into the dangerous wilderness were poor, in addition to being hungry.
Parallels with the Eucharist are also in today’s gospel. It’s Passover time, as it was for the first Eucharist. The crowd’s reclining on the grass anticipates the disciples reclining at table in the Upper Room. Jesus’ taking loaves, giving thanks, and passing them on are the same as his actions at the Last Supper. And the gathering of fragments into baskets, according to ancient interpretation, implies the unity that the Eucharist signifies for the Church.
What the combination of inferences to the hungry poor and the Eucharist seems to be saying to us is this: We who feed on Jesus in the Eucharist are in turn to seek out and feed Jesus in the faces of the poor. Jesus commands us, just as he instructed his disciples: "You give them something to eat."