This type of reaction is a metathesis. It involves double replacement of two reactants to yield two products, one of which is an insoluble product called precipitate. In this case, the complete balanced reaction would be
Al2S3(s) + 6 H2O(l) ⇒ 2 Al(OH)3 (aq) + 3 H2S(s)
Aluminum Sulfide (Al2S3) in room conditions is a solid. When it is dissolved in water, it creates an aqueous solution of Aluminum Hydroxide (Al(OH)3). The insoluble precipitate produced is a solid form of Hydrogen Sulfide (H2S). To know the phase of the reactants, you can refer to the Material Safety Datasheets to know the property characteristics of various elements and compounds.
