"African" is not a language. Africa is a continent that contains 54 countries and more than 2100 completely different languages. Some estimates place the number of languages at around 3000.
If you have any quesitons about African languages, you will have to specify the language.
The most prominent languages spoken in Africa are:
Afrikaans
Amharic
Arabic
English
French
Fula
Hausa
Igbo
Oroma
Somali
Swahili
Yoruba
Zulu
You can say "lafi" to say goodnight in Mandinka.
In Berber, you can say "tanemirt" to say goodnight.
goodnight
"Goodnight".
goodnight!
In Fulani, you can say "Jaama wolof" to say goodnight.
In Pangasinan, you can say "napagtolak" to mean goodnight.
shab bekheyr
In Polish, you say "dobranoc" to wish someone goodnight.
In British English, you can say "goodnight" or "night" as a shorter version.
In Sondhi, you can say "ດີ່ນກັນ" (dien kan) to say goodnight.
goodnight is "bonne nuit" in France.