This is Roger Waters' ode to alienation.
The opening to the second half of "The Wall" sees the narrator trying to connect with the audience, trying to make some kind of contact with any human being. But the isolation he feels from his audience is too great, and the worms (the metaphorical representations of his evil thoughts) begin to eat into his mind.
This song is notable for its David Gilmour fretless bass solos…
Hey you out there in the cold
Getting lonely getting old
Can you feel me?
Hey you standing in the aisles