This is the 3567th most frequent Swedish word.
fattas
"Fattas" means "to be missing" or "to be lacking."
Here, 'fattas' is used to indicate that something necessary is absent or lacking.
Det fattas en viktig del av pusslet.
A crucial piece of the puzzle is missing.
In this case, 'fattas' means to be missing or going wrong, used in an interrogative context.
Vad fattas, varför fungerar det inte?
What is missing, why isn't it working?
'Fattas' is again used to suggest the absence of something, implying a sense of incompleteness.