What does Genesis 6:21 mean?

God's last instruction to Noah in this extended passage has to do with the practical matter of food. In addition to building the ark and planning for all the animals that will come to the ark to be saved, Noah must consider what food will be necessary for the journey. He and his family will need to acquire and store every kind of food that the animals, birds, and insects will need to eat, and they will need to stockpile enough of it to last for the duration of the trip.

As with other parts of the story, specific details are not given. We don't know what specific kinds of foods were to be brought. All we know is that God's covenant promise to save Noah and his family would require Noah to accept certain responsibilities. Among these are the need to build, plan, store, schedule, and do all the work necessary to be prepared when the floodwaters came.