There is no word 'ella' to mean no(or it should be a different transliteration of 'illa') I will try to explain the difference between 'illa'(ഇല്ല) and 'alla'(അല്ല) through examples. Question:"Do you have children?(ningalkku kuttikal undo?) Answer: "illa"(no, (I don't have any children) Question:"Is that a bird?"(athoru pakshi ano?) Answer : "alla, athoru pakshi alla(no, it's not a bird) Question:" Do you know the answer?(ninakk utharam ariyamo?) Answer :"illa,enikk utharam ariyalla" So, generally 'alla' is used to negate something ,or to say something is 'wrong'. In all other cases 'illa' is used.