Three men, one holding pipes, another holding a large object above his head, and one resting against the pipe bed on the truck, are looking at the camera.
three men look at the camera
Three men look at the camera is a rephrasing of three men looking at the camera.
Answer: The three men here include one holding pipes, one holding a large object above his head and one resting against the pipe bed on the truck.
One, another and one are three men, and are looking is a paraphrase of look.