There are 7 continents on the planet Earth. The largest continent is Asia. Africa is the 2nd largest continent. It's three times the size of the United States.
Africa has five big rivers. The top three are the Nile, the Congo, and the Niger.
Africa borders two oceans, the Atlantic and the Indian. It has thousands of miles of coastline, but very few natural harbors. If you were traveling by boat and tried to pull into shore, you most probably would be tossed against the huge rocks along the coastline. This provided a natural barrier for Africa, to protect the continent from invasion.
For all its size, Africa has some mountains, like the Atlas Mountains in the south, but compared to other mountain ranges like the Alps in Europe, Africa's mountains are not very big.
Africa is home, however, to the longest river (the Nile) and the largest desert (the Sahara, the famous Sea of Sand) in the world. Other parts of Africa are rainforests, grasslands and savannahs, and forests. Africa is a diverse place.