In plain words
As for service to the world, its first step is to understand this: that each person should practise their own dharma. Grasping that, one attains true blessedness in this world. When a person practises their own dharma correctly, that very act becomes a benefit — to oneself and to another alike. Dharma is nothing but the customary practice of one's own country and tradition; it is nothing different from this, and we must understand as much. In every one of our customary observances, an element of service to the world is already embedded. Beginning with the aphorism 'now, then, the inquiry into karma,' this fully unfolds the whole great mystery of the doctrine of karma. To perform acts of charity and dharma is a most excellent deed — but one must know that even in this, self-interest is embedded. It means this: that a person stores away the fruit of the karma he himself has performed, for his own experience in a future birth. This is what scripture sanctions, and it becomes clear that whatever karma anyone performs, it is only ever for their own self-interest, never truly for another's sake. This is the supreme truth. In the very beginning, the jīva cannot grasp this supreme truth. Thinking he is doing some good for others, he becomes proud, swells with elation, and struts about in vanity. This is the mark of ignorance, the prompting of naivety, the drama of Māyā.
The Vedic scriptures lay down their injunction-and-prohibition framework concerning non-violence, compassion for all beings, service to the world, and acts of charity and dharma. It is to this very thing that the revered Vidyāraṇya gave the name 'the essence of Bharatiya Vijñāna.' Vijñāna is