Simplify the following text for a Grade 6 native English-speaking person.
Original: Kofi Atta Annan ( ; born 8 April 1938 ) is a Ghanaian diplomat who served as the seventh Secretary-General of the United Nations from 1 January 1997 to 31 December 2006 .
Simplified: Kofi Annan ( born 8 April 1938 in Ghana ) was the Secretary-General of the United Nations . His term began in 1 January 1997 and ended on 1 January 2007 .