Simplify the following text for a Grade 11 native English-speaking person.
Original: â '' Line 4 , currently known as Trinitat Nova â `` La Pau , usually called `` lÃ nia groga '' ( yellow line ) , is a line in the Barcelona Metro network operated by TMB , and part of the ATM fare-integrated transport network .
Simplified: Line 4 , currently known as Trinitat Nova â `` La Pau , usually called `` lÃ nia groga '' ( yellow line ) , is a line in the Barcelona Metro network operated by TMB .