I assume this is in solution (in water). Both zinc chloride and sodium sulfide are soluble. So in solution zinc and sulfide ions will meet and react to form the insoluble zinc sulfide (ZnS).
Zinc sulfide (or zinc sulphide) is an inorganic compound with the chemical formula of ZnS. This is the main form of zinc found in nature, where it mainly occurs as the mineral sphalerite. Although this mineral is usually black because of various impurities, the pure material is white, and it is widely used as a pigment.