What does Genesis 8:12 mean?

In this passage, Noah has sent a raven and two doves out from the ark to search for dry land. Sailors used to use this trick to find dry land. Birds which came back did so because they were too far from a place to comfortably rest. The assumption was that if the bird did not return, it must have found a place to land. That would mean that the earth had become dry enough following the flood to support life again. The last dove sent out by Noah returned, but with a bit of olive leaf caught in her beak. This was hard evidence, for Noah, that the earth was dry enough that plant life had once again begun to grow.

After another seven days, Noah sends out another dove. This one never comes back. She was the first occupant of the ark to find a home back in the outside world. For Noah and the others, that meant it was time to start planning to disembark and begin life over again.