Seven years of great abundance are coming throughout the whole land of Egypt.
The seven good cows represent seven years, and the seven good heads of grain represent seven years. Both dreams have the same meaning.
But seven years of famine will occur after them, and all the abundance will be forgotten in the land of Egypt. The famine will devastate the land.
Joseph stored up a vast amount of grain, like the sand of the sea, until he stopped measuring it because it was impossible to measure.