Hydrogen sulphide reduces a brownish.yellow sptution ef iron(III) chloride to a green solution of iron(II) chloride. The hydrogen sulphide itself is oxidized to sulphurand hydroge chloride. Iron(III) to iron(II) is gain of electron, the process is reduction i.e. $F{e}^{3+}$ is reduced to $F{e}^{2+}$