وَلَمَّا بَلَغَAnd when he attained,in reference to Prophet Yusuf, peace be upon him,أَشُدَّهُhis full manhood,sound in mind and perfect in body,اتَيْنَاهُ حُكْمًا وَعِلْمًاWe gave him wisdom and knowledge,which is the Prophethood that Allah sent him with for the people he lived among,وَكَذَلِكَ نَجْزِي الْمُحْسِنِينَthus We reward the doers of good.because Yusuf used to do good in the obedience of Allah the Exalted