तथा thus, तस्य that Rama, तत्र there, आसतः while sitting, उपयायिनः approaching, भरतस्य Bharata's, सैन्यरेणुश्च dust raised by the army, शब्दश्च and tumult, नभस्पृशौ both reaching the sky, प्रादुरास्ताम् was generated.

Now as Rama was sitting there, the tumult and the dust raised by the approaching army of Bharata reached the sky.