'Thus, my dear son, there was one part of the sixteen parts left to you, and that, lighted up with food, burnt up, and by it you remember now the Vedas.' After that, he understood what his father meant when he said: 'Mind, my son, comes from food, breath from water, speech from fire.' He understood what he said, yea, he understood it.

In plain words: The father explains that Svetaketu's one remaining part was fed by food and blazed up again, so he could remember the Vedas. Now Svetaketu truly understands his father's teaching: the mind comes from food, breath from water, and speech from fire.