Lacquer consists of certain polymers which are dissolved in a solvent. Once applied to a surface, this solvent evaporates leaving behind the polymers which give the surface the shining, smooth finish that you see. These polymers also have the colors etc as required. Multiple coats of this lacquer is applied to ensure that the finish smooth and long lasting and this process is a little time consuming.Compared to Polyurethane polish more popularly known as PU, lacquer is easier since the drying solvent ensures that fewer brush strokes or spray marks are visible compared to PU. In addition, lacquer dries faster which prevents external impurities from getting embedded (though that is avoided everywhere by ensuring minimum other work is going on while this polishing happens.