In the further part of the game (starting with the 13th main mission titled Pitch Dark) the Metal Gear Solid V action is moved to Africa. It is a problem since you are going to be forced to "learn" a local language to interrogate imprisoned enemies. You can learn the Afrikaans language in two ways which are described below.
The first option is to capture a translator during the 14th mission of the game titled Lingua Franca. You can knock him down and fulton away at the beginning of the mission or later on, when he will be focused on getting to other hostages. You may recognize him because of his green beret.
The second way is related to the Side-Op focused on capturing a translator which will be unlocked as the number 3: Extract Interpreter (Afrikaans). This mission will begin close to the Blampeve Plantation in Africa. After getting there begin a reconnaissance. The translator is close to the hut show on the screenshot above. Knock him down and fulton him to Mother Base.