Kumara is a word that approximates the english "heir," or "groom," it also signifies a river, or a kind of bird (a type of parrot). Sanat is a word that signifies "from always/forever ago," and is a nickname for Brahma. Sanat-kumara is the heir of Brahma, and in the Puranas is both the son of Brahma (heir) and the one who presents Brahma (as a "groom" would) to our humanity (not species, nor world, but the human state of being). When Narada is speaking to Sanatkumara, it is intended as a double-meaning, double entendre: it is both a literary tool to convey Brahma (something which cannot be directly comprehended from human limitations of sight, sound, touch, taste, smell, and thought) through an indirect intermediary, and also instructive of an abstract concept of intermediate and indirect observation, a system of logical deduction, reduction and inference.
We must approach what is unknown through what is known. Even if all we have studied is dance, we have learned the scientific methods required to understand other things. It is the method of logic which yields knowledge, not experience. However, experience is an expedient means: the ancients practiced, besides logic, a system of belief. Belief is founded in experience. Krishna and Gotama both instructed in a system of letting go of these beliefs (through Sannyasa) by a ritual of sacrificing (letting go/sannyasa) to the directions (as Sanatkumara does here), but there are differences in both purpose and method in how a Brahmin (a student of Brahma's various manifestations/children) and a Vishneva (a student of Vishnu's various manifestations/avatara) practices these same sacrifices.
Sanatkumara advocates a system of spirituality (not in the western sense, but in terms of spirit teachers, i.e. veneration of the spirits through Bhakti Yoga), a taking up of Spirits, to manifest Brahma - whereas a Vishnava would practice letting go of spirits to manifest Vishnu.