According to Osho, "yes" means saying a total, trusting acceptance to existence - dropping the ego, opening like a flower, and melting into the whole. It is the essence of religion and the doorway to meditation: trust, relax, and align with life. In contrast, "no" is resistance, separation, conflict, and a windowless prison of the mind.
Saying yes means trusting life, letting go of your ego, and relaxing into what is instead of fighting it.