pasyadityan vasun rudran
asvinau marutas tatha
Word for word:
pasya — see; adityan — the twelve sons of Aditi; vasun — the eight Vasus; rudran — the eleven forms of Rudra; asvinau — the two Asvinis; marutah — the forty-nine Maruts (demigods of the wind); tatha — also; bahuni — many; adrsta — that you have not seen; purvani — before; pasya — see; ascaryani — all the wonders; bharata — O best of the Bharatas.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O best of the Bharatas, see here the different manifestations of Adityas, Vasus, Rudras, Asvini-kumaras and all the other demigods. Behold the many wonderful things which no one has ever seen or heard of before.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Even though Arjuna was a personal friend of Krsna and the most advanced of learned men, it was still not possible for him to know everything about Krsna. Here it is stated that humans have neither heard nor known of all these forms and manifestations. Now Krsna reveals these wonderful forms.