Dear student,
To seperate salt from sand the easiest method is dissolving salt in water and filter it out and then heat the solution.
Put the mixture into excess water and stir the mixture thoroughly so that the entire salt in the mixture get dissolved in water. Then seperate the salt solution and undissolved sand using some filter nets.
Now take the salt solution and heat it properly. Then the water present in the solution will get evaporated and pure salt will be settled at the bottom of the vessel.
This is the easiest method to seperate sand and salt