As of 2014, roughly 40% of the adults in Africa are illiterate.

Illiteracy in Africa is common, with approximately 40% of all African
adults (about 153 million people) who are unable to read or write as of
2015. Nine out of the top 10 countries with the highest illiteracy rates
are from Africa. Women are more likely than men to be illiterate;
two-thirds of all illiterate adults in Africa are female. From 1990 through
2008, the literacy rate for adults in Africa improved from 52% to about 60%
due to increased advocacy, however, the total number of illiterate adults
actually increased from 177 million to 200 million. This is likely a result
of the continent’s rapidly growing population, which is projected to
double by 2050.