@@maleehaaamir1708 a heart of marble is basically used here as a metephor it is referring to a stone hearted person or a person who is heartless, keeping this drama and song which was written for this drama that is "sange mar mar ka ghar" in mind the song is refering to the storyline of this drama which depicted people who were heartelss and stone hearted people of the typical tribal areas of Pakistan that is the north western frotier province now kpk in which a mens two of his sons die, daughter gets divorced and daughter in law gets married to his son in law and in the the mother in law kills his son in law who by manipulation killed both of his elder sons and thus the last son leaves the house, it showed how such a tragedy and loss occured with the individuals of that house but they kept thinking in the end with silence and without tears that how did this happen and why us and thus similarity the song is entitling this towards those heartless people. I hope you now understand.