Simplify the following text for a Grade 5 native English-speaking person.
Original: John Lester `` Johnny '' Nash Jr. ( August 19 , 1940 - ) , is a American reggae and soul singer .
Simplified: John `` Johnny '' Lester Nash , Jr. ( born August 19 , 1940 ) is an American pop singer-songwriter , best known for his 1972 hit , `` I Can See Clearly Now '' .