Simplify the following text for a Grade 6 native English-speaking person.
Original: Brian Thomas Littrell ( born February 20 , 1975 ) is an American singer-songwriter , best known as a member of the Backstreet Boys .
Simplified: Brian Thomas Littrell ( born February 20 , 1975 ) is an American singer . He is best known as a member of the Backstreet Boys .