धर्मात्मा: righteous self, सः that, विभीषणः Vibheeshana, हृष्टः happily, खात् from the sky, भक्तेः devotees, सहा: accompanied by, अवनिम् on to the land, पपातात: descended, रामस्य: towards Rama, निपपात: fell on the feet.

Righteous Vibheeshana descended from the sky and fell at the feet of Rama accompanied by his devotees happily (considering it to be inappropriate to come with foot down he came straight down with his body).