the 7 fat cows means there would be 7 years of good crops
the 7 skinny cows symbolises the 7 years of drought
The pharaoh also had dreams; the same dream every night. He had magicians, sorcerers, everyone he could think of who could interpret the dream. But to no avail; until the butler told the pharoah of Joseph.
Joseph was released from jail and interpreted the pharaoh's dream. The pharoah was so happy that Joseph interpreted his dream that he changed Joseph's name to Zaphenath-paneah and promoted Joseph to be in charge of the looking over the grains
The drought came. One day, 10 Canaan brothers came to collect some grains. Joseph recognised them, but the brothers didnt. Joseph asked if all of the brothers were here, but they said no. Joseph then sent them back to get the one brother and held Simeon captive.
The brothers came back with Benjamin and Joseph gave them their grains, but he got his slave to put his goblet which the pharoah gave to him in Benjamin's grain bag. He then told his guards to search for the goblet which was in Benjamin's bag. It was a setup.
The guards found the goblet in Benjamin's bag, and the brothers were sent back to Joseph. Joseph threatened to kill Benjamin but Judah was willing to sacrifice himself for Benjamin, saying it would break his father's heart.
Joseph revealed himself as their long lost brother and they celebrated. The pharoah; hearing of the reunion, and favourites Joseph, invited Joseph's whole family to move to Egypt, and they did.