Those coordinates represent a single point, not a whole continent. The point is in southern Chad, in the interior of the African Continent. Any other point, in Africa or anywhere, has different coordintes.
Africa is located at latitude 20°E and longitude 20°N.
Since you did not specify the direction of longitude, the country located at 20 degrees south latitude and 140 degrees east longitude is Australia, while the country located at 20 degrees south latitude and 140 degrees west longitude is France. The location is French Polynesia, which is a French territory.
The country that is located at 65 degrees North latitude and 20 degrees West longitude is Iceland. The country that is located at 65 degrees North latitude and 20 degrees West longitude is Iceland.
The latitude and longitude for 46 degrees North latitude from the Prime Meridian are approximately 46 degrees North latitude, 0 degrees longitude. Moving to 21 degrees South, 35 degrees West would take you to approximately 21 degrees South latitude, 35 degrees West longitude. Continuing to 20 degrees South, 45 degrees West would position you at approximately 20 degrees South latitude, 45 degrees West longitude. Finally, moving to 20 degrees North would bring you around 20 degrees North latitude, along the same longitude as the previous location (45 degrees West).