In the context of place names like Luton or Sutton Hoo, "Hoo" signifies that these settlements were located on or near a hill or elevated area. For example, Luton is believed to have derived its name from the Old English words "Lygan dun," which means "hill of lies," referring to the town's location on a hill.
Similarly, Sutton Hoo, an archaeological site in Suffolk, England, is named after the nearby Sutton Hoo Hill. The name "Hoo" in this case indicates that the site is associated with the hill.