i need a help =" please ="

hi every one <3 , i wanna ask 你 about a song and i hope 你 can help me to know it ="
link
it is started from 3:01 to 3:11 ="

when Jeon Ah-min(Jo In-seong)with Ham Eunjung(Yoon Baek Hee) and the Teacher , the Teacher 说 : start ,
then Jo In-seong say the song ( the english lyrics in this part is :
( 嘿 , just like i believe in 你 believe in my friend , therefore i to not be burdened to introduce 你 to my 老友记 )
then the Teacher 说 : let it out , let it out

你 know it ? ="