Google Translate, while not nearly as accurate as a professional translator would be, comes handy as it can translate chunks of text in no time and for free. Errors aside, the reader will likely understand most of the translated text right way.
Google Translate expanded last month, when three new African languages were added among others, so the service can now translate ten native African languages. These are : Amharic, Chichewa (Nyanja), Igbo, Shona, Somali, Sotho (Sesotho), Swahili, Zulu, Yoruba and Xhosa. According to Wikipedia, Kinyarwanda and Wolof are under development. In addition, Google Translate includes most foreign-derived languages spoken in various parts of the continent, including Afrikaans, Arabic, French and Portuguese.
While it is nice to have so many African languages, there is only limited amount of content available in the web in those languages, so the service is not as useful as it could be. Many African languages, while commonly spoken, may never have flourished in written form.
Google translate can be used for learning purposes, this works well with most established languages (eg. German, Spanish, French), where the quality of translations is good, as long as the translated text is simple enough. Numerous inaccuracies mean this is not really a good way of learning less prominent languages.
Those who are interested in learning African languages will indeed face the problem of finding suitable learning resources. Many African cities have well-equipped book stores, yet it is difficult to find any books on learning local languages. A better option is to check what is available on Amazon, and order what you want well before your intended trip.
Finding learning material via internet is not easy either. Some volunteer organisations, (e.g. Peace Corps) provide good selection of language-learning material, that is available for free. Then there is Wikipedia, which has editions in various African languages. Even a beginner can learn a lot by reading these articles, particularly if the subject is familiar. It is also worth checking if there are any helpful videos on Youtube.
One should also download the Memrise app, available for Android and iOS, or use its web version. The interface is simple, just repetitive learning of words and short sentences. But the selection of languages in huge, including tens of African languages. It won’t make you a perfect speaker, but will help understanding the basics at least.
The best way, however, to learn a new language is to befriend a native speaker. Most people are much willing to help, once you show you intention of learning his/her language. Technology may be useful, but no the king.