# he is robed in majesty; Yahweh has clothed and girded himself with strength
"he shows everyone that he is a powerful king" or "his majesty is there for all to see, like the robe a king wears; everything about Yahweh shows that he is strong and he is ready to do great work"
# girded himself
put on a belt—a band of leather or another material that a person wears around his waist—to prepare for work or battle
# The world is firmly established
"You have firmly established the world")
# it cannot be moved
"no one will ever move it"