In James Cameron’s Avatar, the Na’vi people on Pandora speak the Na’vi language. Linguist Paul Frommer created Na’vi for the 2009 film, working from sound patterns and grammatical requirements supplied by the production.
Na’vi was designed to sound unfamiliar while remaining pronounceable for actors and audiences. It has its own vocabulary and grammar rather than being ordinary English spoken with an accent. The film introduces audiences to Na’vi through characters including Neytiri and Jake Sully, who gradually learns to communicate with the Na’vi.
The language expanded beyond the first film through additional vocabulary, fan study, instructional resources, and later Avatar productions. “Pandoran” is a general adjective for things associated with Pandora, but it is not the name of the fictional language. “Na’vi” can refer to both the fictional people and their language, so the wording of the question identifies the linguistic meaning.