During the dry season, no rain falls in an area. One only speaks of the dry season when it occurs at the same time of year every year, alternating with a rainy season. Dry seasons only occur in a strip on either side of the equator. North of the Sahara, this strip is called the Sahel zone. But there are other areas like this.
If the dry season is severe, rivers and lakes can dry up partially or completely. Such a valley is called a wadi. There are such in Africa, Asia, and South America, but also in Spain and on the Mediterranean island of Cyprus. Only special animals and plants can survive there. It is also dangerous there: if there is a strong thunderstorm in the headwaters of the river, the river can flood the wadi very suddenly. Animals and people can be carried away.
In other areas, there are dry forests. There is enough rain for about ten months a year for green forests to develop. The ground stores a lot of water. During the two dry months, the trees do not die, they just lose their leaves. This gives a lot of light to bushes. There are not as many different animal and plant species here as in the rainforest, but there is a special diversity of species.