Swahili is the most useful single African language to learn: it is an official language of the African Union and the everyday language of trade across East Africa.
What makes Swahili different
Nouns fall into classes, and the class changes the start of related words — mtu (person) becomes watu (people).
Stress almost always lands on the second-to-last syllable, which makes reading aloud predictable.
Greetings are a small ritual: habari expects a reply of nzuri before anything else happens.
Your first Swahili phrases
Each phrase is written the way it's spelled, then respelled for English speakers with the stressed syllable in capitals.