Bhashya
तत् तस्मिन् यथोक्तेऽर्थे एष श्लोको मन्त्रो भवति-शतंच एका एकोत्तरशतं नाड्यः हृदयस्य मांसपिण्डभूतस्यसंबन्धिन्यः प्रधानतो भवन्ति, आनन्त्याद्देहनाडीनाम् ।ता-सामेका मूर्धानमभिनिःसृता विनिर्गता ।तयोर्ध्वमायन् गच्छ-न् अमृतत्वम् अमृतभावमेति ।विष्वक् नानागतयः निर्यग्वि-सर्पिण्य ऊर्ध्वगाश्च अन्या नाड्यः भवन्ति संसारगमनद्वार-भूताः ; न त्वमृतत्वाय ; किं तर्हि, उत्क्रमणे एव उत्क्रान्त्य-र्थमेव भवन्तीत्यर्थः ।द्विरभ्यासः प्रकरणसमाप्त्यर्थः ॥
In plain words
In this context, there is this verse: One hundred and one channels lead out from the fleshly heart, branching through the vast network of the body. Of these, one rises straight up through the crown of the head. Moving upward through it, one reaches immortality. All the other channels wander in every direction—sideways and up—acting merely as gateways for worldly existence, not for liberation. What then do they do? They serve solely for departure from the body at death. The repetition at the end marks the conclusion of the section.
Close to the Sanskrit
That in this stated meaning, this verse/mantra is: One hundred and one channels of the heart, which is a lump of flesh, are connected principally, due to the infinity of the body channels. Of those, one has issued forth toward the crown of the head. Going upward through that, moving, he attains immortality/the immortal state. Spreading in all directions, sideways and upward, the other channels are gateways leading to worldly wandering; not indeed for immortality; what then? In departure only, for the purpose of departure itself, is the meaning. The twofold repetition is for concluding the section.