# Go into the rocky places

Possible meanings are the people should go into 1) caves on steep hillsides or 2) places where there are many large rocks among which to hide.

# hide in the ground

Possible meanings are that the people should hide 1) in natural holes in the ground or 2) in pits that they dig in the ground.

# from the terror of Yahweh

"to get away from Yahweh's terrifying presence" or "from Yahweh because you will be extremely afraid of him" 

# the glory of his majesty

"the great beauty and power he has as king" or "his royal splendor."