Gross domestic product (GDP) is a measure of a country’s economic output, calculated as total value of goods and services produced by a country’s economy during a specific period of time.
In Year 2021, these were the top 10 countries in Africa, on GDP basis:

SOURCES
http://www.statista.com
http://www.wikipedia.org
http://www.britannica.com
http://www.investopedia.com
http://www.statisticstimes.com
http://www.africa.businessinsider.com