Two men are interacting with some sort of mechanical contraption that is mounted on a wall.
Some men work on a machine on a wall.
Two men indicates that it is some men, mechanical contraption shows it is a machine with which they are working on a wall.
Two men turned into "Some men" due to "some" being interpreted as "more than one" a mechanical contraption is just another way to say "device" or machine
The men are interacting with a mechanical contraption means the men work on a machine.