Simplify the following text for a Grade 7 native English-speaking person.
Original: Liettres is a commune in the Pas-de-Calais department in the Nord-Pas-de-Calais region of France .
Simplified: Liettres is a commune . It is found in the region Nord-Pas-de-Calais in the Pas-de-Calais department in the north of France .