B 737 is correct.
With an FAA certificate you can only fly N registered aircraft, and there are few based in different parts of Africa.
All African states will accept your FAA certificate (most will check with the FAA first to cofirm) as a base to issue a state's own license that would enable you to fly aircraft registered in their country.
The coversion process depends on each country's CAA. Most will require you to do at least
an airlow exam.
Some will require nothing, and I suggest you steer clear of those ones, especially if you are just starting your career as they can ruin it by turning you into a dangerous pilot and you won't be able to fit in "normal" safe environment whenever you decide to pull out. That's if you make it out alive anyway.