sisrksayam-when there was the will to create; tatah-then; nabheh-from the navel; tasya-of Him; padmam-a lotus; viniryayau-came out; tat-nalam-its stem; hema-nalinam-like a golden lotus; brahmanah-of Brahma; lokam-the abode; adbhutam-wonderful.
When Visnu lying in the ocean of milk wills to create this universe, a golden lotus springs from His navel-pit. The golden lotus with its stem is the abode of Brahma representing Brahmaloka or Satyaloka.
"Gold" here means the dim reflection of pure cognition.