Philosophical ethics presents a multitude of theories to try to answer that question. The answer lies in the nature of the human being. The traditional answer is happiness with God. The branch of theology that studies human acts so as to direct them to a loving vision of God seen as our true, complete happiness and our final end. This vision is attained by means of grace, virtues, and the gifts, in the light of revelation and reason.
Moral theology is teleological Teleology deals with the end or purpose of something.
That will give us an idea about the meaning of justice. We need to expand our definition to include this world. The telos of the human person. The realization of one s potential as a human being. This happens on four levels.