In plain words
The human body is full of nine openings; through it the breath of God's Name must flow without ceasing
In those days the music of the flute with nine openings in Kṛṣṇa's hand cured the illnesses of the body and the diseases of the mind. Its inner meaning tells us that the human body itself is full of nine openings, and that the breath called God's Name must keep flowing through it. Moreover, every single opening needs the touch of God's hand. From that touch the saying arose, “sparśanaṃ pāpa nāśanaṃ.” That is why the gopīs kept saying this:
Sing a song, Kṛṣṇa, so that Your words drip honey; speak, Mukunda, till our hearts are content. Draw out the whole essence of the Vedas and turn it into Nāda Brahman; pour it back into the flute and turn it into the form of song: sing a song, Kṛṣṇa, so that Your words drip honey; speak, Mukunda, till our hearts are content.
“Kṛṣṇa! Make our very bodies Your flute! Let Your in-breath and out-breath move freely within this body. Your in-breath and out-breath are themselves the essence of the Vedas. When You put this essence of the Vedas into the body, it becomes the essence of song. Let us hear such song,” they said.
Whether the song of a spring cuckoo, the singing of M.S. Subbulakshmi or that of P. Leela, it was none of these. They asked Him to let them hear the song of the Vedas. Our body is a flute. Just as this flute has nine holes, the body too has nine openings. In it, God's Name is the essence. It must flow all through, from the tips of the nails to the crown of the head. God's touch must be in everything. So all the limbs must be offered in God's service alone. This itself they called “sarva karma bhagavatprītyarthaṃ.”