Xhosa vs African

Xhosa and African both are nouns.

Word	Noun	Adjective	Verb	Adverb
Xhosa	Yes	No	No	No
African	Yes	Yes	No	No

As nouns, African is a hypernym of Xhosa; that is, African is a word with a broader meaning than Xhosa:

Xhosa (noun)	African (noun)
a Bantu language closely related to Zulu, it is the second most common home language in South Africa	a native or inhabitant of Africa
a community of Negroid people in southern South Africa
a member of the Negroid people of southern South Africa

Xhosa (adjective)	African (adjective)
	of or relating to the nations of Africa or their peoples