compare and contrast the two prevailing winds that blow over Afica in June and September?

2 answers

Whoever assigned that question should realize that Africa has many latitude zones: above, below and near the equator. The answer depends upon what zone you are talking about. Prevailing winds are westerly in temperature zones and "trade winds" in subtropical zones, all year long.

For more about prevailing winds, see
http://www.newmediastudio.org/DataDiscovery/Aero_Ed_Center/Charact/Prevailing_Winds.html

Month-to-month differences in prevailing winds are another matter. They can be important in equatorial regions (e.g. monsoons)
I meant to write:

Prevailing winds are westerly in TEMPERATE zones. (Not temperature zones).

North and South Africa are in temperate latitude zones. So is most of the United States, Australia and Europe