A very touching song! And as usual it's beautifully sung by Kishore Kumar.
I won't go into details of any kind today. I'll just write my favourite lines:
'Zindagi tou bewafa hai, eik din thukaraaegii
Maut mehbooba hai, apnay saath lay kar jaegii
Mar kay jeenay ki ada jo duniya ko sikhalaega
Woh muqaddar ka Sikander jaanemann kalalaaega.'
I guess you're born with that quality...you can't work on it. 'Mar kay jeena ki ada' tou bohat kaam logon mein hoti hogi. As it is, most of the people are already dead & they don't even know it.