दशरथात्मज: son of Dasaratha, दुर्धर्ष: unassailable, राम: Rama, यदा when, घोरम् dreadful, एतत् वनम् this forest, आगमिष्यति will come, तदा then, पूता भविष्यसि you will be purified.
'When the son of Dasaratha, the unassailable Rama enters this dreadful forest, you will be cleansed (of this sin)'.