The sentence 'Postquam sex annos in Italia exercitui praefuit Romani eum exercitui Hispanio praefecerunt' means After he had been in command of the Roman army in Italy for six years, they appointed him to the army in Spain. In the word-by-word translation, the conjunction 'postquam' means 'after'. The adjective 'sex' means 'six'. The noun 'annos' means 'years'. The preposition 'in' means 'in'. The noun 'Italia' means 'Italy'. The noun 'exercitui' means 'army'. The verb 'praefuit' means '[he/she/it] was before, presided over'. The noun 'Hispanio' means 'Spain'. The verb 'praefecerunt' means '[they] set over, appointed'. The pronoun 'eum' means 'him'. The noun 'Romani' means 'Roman'.