It means - "The Gospel According to Matthew, chapter six"
Much of Matthew chapter 6 was from the 'Q' Document, and also appears in Luke's Gospel.
Matthew was a Jew.
Matthew Krohn is 6' 6".
Matthew Van Howe is 6' 6".
Matthew Willig is 6' 6 1/2".
Matthew Mancinelli is 6'.
Matthew Malliski is 6'.
Matthew Lamothe is 6'.
Matthew Lopes is 6'.
Matthew Lowd is 6'.
Matthew Jackowski is 6'.
Matthew Jure is 6'.
Matthew Janega is 6'.