Well it ain’t. It does not melt ice. Salt is just moving the melting point below 0 degrees Celsius and thus you will see water becoming liquid when salt comes into play.
The way ice make water liquid is by injecting the sodium and chlorine ions between the water molecules in the ice breaking it apart. If I may, I’d name this ice crunching or ice braking, but not ice melting.
Anyways, salt helps only if the temperatures are -7 degrees or above. Below that temperature you need to use some other substance like potassium acetate or magnesium chloride. Salt and these other ice breaking substances aren’t doing any good to the environment so we need to take great care when using and then disposing of it.