Complex sentence: The penalty flag (or "flag") is a yellow cloth used in several field sports including American football and lacrosse by game officials to identify and sometimes mark the location of penalties or infractions that occur during regular play.
Split into simpler sentences: The penalty flag (or "flag") is a coloured cloth used in several field sports. A yellow coloured flag is used in American football by game officials to identify and sometimes mark the location of penalties or infractions that occur during regular play.