Coverb has a number of distinct uses in
linguistics.
As used in Chinese linguistics in America. it goes back to Tewksbury's Speak Chinese of 1948 (compiled 1943-45), p. 53.
As used in the linguistics of native Australian and American languages, its meaning there is a kind of neutral element which can become either verb or noun depending on what it is combined with.
Chinese pedagogists trained in the US do translate "coverb" occasionally as gong4-dong4-ci2, but the preferred term is jie4-ci2, which was Ma Jianzhong's translation of English "preposition". The Chinese coverb is a preposition-like particle that generally appears to have originated as a verb, and describe the coverb-noun phrase as a type of adverbial.
Tewksbury's explanation is very much more subtle than that: "A co-verb indicates a relationship between a noun and the main verb. It functions like an English preposition, and never receives stress in speaking. The co-verb and its object always precede the main verb, and form a setting for the action of the main verb."