i need a help =" please ="

hi every one <3 , i wanna ask te about a song and i hope te 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 detto : start ,
then Jo In-seong say the song ( the english lyrics in this part is :
( ciao , just like i believe in te believe in my friend , therefore i to not be burdened to introduce te to my Friends )
then the Teacher detto : let it out , let it out

te know it ? ="