The English language teaching situation in Africa is at best rather confusing. Many ex-colonies of Britain use English as the medium of instruction in state schools and so most teachers are locals. Some advanced level positions may be available in universities in such locations. In other African countries English is much in demand but few schools are able to afford a native speaker teacher and so positions are largely filled by voluntary workers (though sometimes paying a 'local' salary). There are many placement organizations that can arrange voluntary work in Africa should that be your aim.
There is some work available in South Africa but as many of their citizens speak English as a native language, opportunities for non-South Africans are somewhat limited. Zimbabwe used to offer a number of possibilities but recent political events have curtailed most EFL activity.