“Ah well, um—because I’m dying—in that canning factory.
(off Newt’s look)
Everyone there’s dying. It just crushes the life outta you. You like canned food?”
-- Jacob Kowalski (WTF)
The canning factory is the place where Jacob Kowalski works before trying to open his own bakery and befriending Newt Scamander.
The canning factory is referenced in Scenes 9, 50, and 121 of the Fantastic Beasts screenplay.
Jacob Kowalski cannot stand working at the canning factory because it is monotonous and grueling work. Instead, he dreams of opening his own bakery because he loves baking and food makes people happy.