the second-longest river in africa is the congo

is in africa an adjective or an adverb phrase

What is it describing?

the second-longest river right? so its and adjective phrase.

right

"In Africa" in the given sentence is a prepositional phrase functioning as an adverbial phrase.

To identify whether a phrase is an adjective phrase or an adverb phrase, we need to determine what it is modifying. In this case, the phrase "in Africa" is providing information about the location of the river, the Congo. It tells us where the river is located.

Since the phrase is modifying the verb "is," indicating the location or position of the subject, it is acting as an adverbial phrase.