The 'black land' was the land on the banks of the Nile where the Ancient Egyptians used the land for growing their crops. It was the only land in Ancient Egypt that could be used for farming because a layer of rich, black silt was deposited there every year after the Nile flooded.
The 'red land' was the barren desert land that protected Egypt on two sides. The desert lands kept Ancient Egypt from neighbouring countries and invading armies. The desert also gave the Ancient Egyptians a source of precious metals and semi-precious stones.
I hope this answered your question and I apologise if I am wrong. Good luck on your assignment :)