What does Luke 9:15 mean?

The day began to wear away; and the twelve came, and said to him, “Send the multitude away, that they may go into the surrounding villages and farms, and lodge, and get food, for we are here in a deserted place.”

But he said to them, “You give them something to eat.” They said, “We have no more than five loaves and two fish, unless we should go and buy food for all these people.”

For they were about five thousand men. He said to his disciples, “Make them sit down in groups of about fifty each.”

He took the five loaves and the two fish, and looking up to the sky, he blessed them, and broke them, and gave them to the disciples to set before the multitude.

They ate, and were all filled. They gathered up twelve baskets of broken pieces that were left over.

As he was praying alone, the disciples were with him, and he asked them, “Who do the multitudes say that I am?”