You should watch the movie to determine what the title refers to. You cannot truly know the meaning of something without its context. I believe you are referring to the 2018 film Terminal, and through reading the plot summary on IMDb, you can pick out clues:
In the dark heart of a sprawling, anonymous city, TERMINAL follows the twisting tales of two assassins carrying out a sinister mission, a teacher battling a fatal illness, an enigmatic janitor and a curious waitress leading a dangerous double life. Murderous consequences unravel in the dead of night as their lives all intertwine at the hands of a mysterious criminal mastermind hell-bent on revenge.
The following lines stick out to me:
two assassins carrying out a sinister mission
a teacher battling a fatal illness
Looking at the dictionary definitions of "terminal" from OED:
a. Occurring at the end (in time or serial order); forming the last
member of a series or succession; closing, final, ultimate.
(b) Of an individual: affected with a terminal disease or the
terminal stage of a disease; close to death, moribund.
Based on the synopsis of the movie (and without watching it), I would believe the title is intentionally ambiguous and refers to multiple "terminal" events in the film. The "teacher battling a fatal illness" is the clearest use of terminal that I see, though it is also likely playing on the other "murderous consequences." There may very well also be a scene in an airport terminal, but you would not know that without watching the movie.
TL;DR: Watch the movie, then form your interpretation based on the information you absorbed. Your opinion may differ from someone else's; that's part of film criticism. The same thing applies to books—why did the author decide this title? What does it mean? Read the book for context, then use that information to make an argument for your interpretation of the title.
EDIT: To answer your question about the film "The Terminal," you can read the synposis:
An eastern immigrant finds himself stranded in JFK airport, and must take up temporary residence there.
The title clearly refers to the fact the film takes place in an airport terminal, hence the title refers to that specific terminal.