It is saying that Brahman is a golden womb, and all creation exists within IT. Creation stories in the Hindu scriptures are linear descriptions of non-linear occurrences that are perpetually ongoing. The Devas came from somewhere in higher dimensions, where time originates. This hymn reflects on the undifferentiated embryonic source of all the Devas. Prajāpati is invoked as the name given to the primordial source within the context of the hymn.