This shloka continues the thought from 5.8. Speaking, letting go, grasping, opening the eyes, closing them — it all goes on. And the yogi holds firm to this understanding: the senses are simply doing their work with their objects. That is all.
A ceiling fan spins, air flows. But the electricity is just a medium. In the same way, the yogi's senses keep functioning, yet the yogi stands apart — a witness, not a participant.