Sodium chloride, a common salt, dissolves in water due to the attraction between the negative part of the water (oxygen) and the positive part of the salt (sodium). Similarly, there is also an attraction between the positively charged part of water molecules (hydrogen) and the negative chloride atoms.
When a solid salt (sodium chloride) is placed in water, the forces of multiple water molecules on salt molecules work to break the bond between sodium and chloride. As more salt is added and dissolved, there are fewer free water molecules to facilitate dissolution. After the point of saturation, which depends on temperature and pressure, no more salt will dissolve into solution.