The arm is a metonym for the strength in the arm. Alternate translation: "strength like God's strength" (See: [[rc://en/ta/man/translate/figs-simile]])
God uses this rhetorical question to show Job that God is powerful and Job is not. Alternate translation: "You certainly cannot thunder with a voice like God's." (See: [[rc://en/ta/man/translate/figs-rquestion]])
Here "thunder with a voice" is a metaphor for speaking in way that is extremely loud and frightening like thunder. Alternate translation: "Can you speak with the sound of thunder as he does" (See: [[rc://en/ta/man/translate/figs-metaphor]])