Complex sentence: Bill Keller (born January 18,1949) is a writer for "The New York Times", of which Keller was the executive editor from July 2003 until September 2011.
Split into simpler sentences: Bill Keller (born January 18,1949) is an American journalist. He is a writer for "The New York Times", where he was executive editor from July 2003 until September 2011.