To cut the grass in a lawn
A lawn mower is a machine used to cut a lawn to an even length. Lawn mowers were among Arthur Weasley's junk which escaped to the Ottery St. Catchpole forest. A lawn mower is found in the Muggle Studies classroom at Hogwarts School of Witchcraft and Wizardry. During the summer of 1997 the Muggle next-door neighbour to the Dursleys was using a lawn mower and was shocked when Harry Potter yelled.