button clicked to set text in another form

[vanduongbk]

hi nix, i dont know what is emit
and you can a demo code for void transfertCompleted(QString)

in form1,i have a private slot as:
void form1::on_pushButton_clicked()
{
//some a calculate and write a data ro uart here
//i want to write text to mainform
}

i want to do that when i click button ,it will send data to uart and in mainform ,qlabel text is set as "sent complete"
thank