how is salt a good conductor of heat ?

salt is not a good conductor of heat. saltwater is a good counductor of heat as:

Saltwater is a good conductor of electricity because it is an ionic solution. The mobile ions can act as charge carriers which allow an ionic solution to support current flow. Salt is an ionic substance, meaning it breaks up into ions when dissolved and it has Na+ (sodium) and Cl- (chlorine) ions present in it, therefore being able to carry a charge through the ions.

Hey, actually salt is neither a good conductorof heat nor electricity. Salt when dissolved in water roduces ions and thereby salt water is a good conductor of heat as well as elecctricity.