What is WALL-E's primary job on Earth?

WALL-E’s primary job on Earth is compacting trash. His name is an acronym for “Waste Allocation Load Lifter: Earth-Class,” describing the robot’s purpose as a garbage-processing machine.

Humanity left Earth after Buy n Large covered the planet with waste and pollution. The company deployed fleets of WALL-E units to compress the rubbish into orderly cubes and clean up the surface. By the time the film begins, nearly all of the robots have stopped functioning. The solitary remaining WALL-E continues his assigned work, while collecting unusual objects that catch his attention.

His job explains the film’s visual world: the Earth is filled with towers of compacted garbage, while WALL-E methodically builds more. It also contrasts with his developing personality. Although designed for repetitive labor, he becomes curious, forms an attachment to a cockroach named Hal, and falls in love with EVE. His routine ultimately leads to the plant that could make Earth habitable again.