Isaiah continues to describe his vision.
Each one called to another and said
“The seraphim called out to one another and said” or “The winged creatures proclaimed to one another”
Holy, holy, holy, is Yahweh of hosts
Repeating the word “holy” three times indicates God is completely holy. AT: “Yahweh of hosts is holy beyond all else” or “Yahweh of hosts is completely holy”
The whole earth is full of his glory
This speaks of the earth as if it were a container and glory were the contents in the container. AT: “Everything on the earth is evidence of God’s glory” (See: rc://en/ta/man/translate/figs-metaphor)