And it could mean any number of things since it's so vague. Posted by Marc Guggenheim, one of the show runners earlier this morning was an image of the script, which he followed up with another picture of the cast doing the last table read of the season.
Edited to add the names of the four episodes leading up to the finale:
19. Broken Arrow
20. The Fallen
21. Al Sah-him
22. Is This Your Sword