Alternate reality
Jeanine was an alien female who, in the alternate reality, was serving in the operations division aboard the USS Enterprise shortly before that starship was destroyed in 2263.
Jeanine was later held captive in Krall's base. Outside but on the grounds of the facility, she witnessed Manas remove the Abronath from Ensign Syl's head, the bioweapon having been hidden from their captors there. Freed by Spock and McCoy, Jeanine was in the last group of Starfleet officers which escaped from the base. They were protected by Captain James T. Kirk using a motorcycle and holographic technology, moments before the group was beamed to safety aboard the USS Franklin. (Star Trek Beyond)
Jin on the cover of Prosthetics magazine
Her face was featured on the cover of Prosthetics magazine issue 4, which referred to this character as "J-Nine" (p. 3). Star Trek Beyond - The Makeup Artistry of Joel Harlow (pp.103) clarifies that J-9 is short for "Jeanine".