Possible meanings are 1) "God has made his angels to be spirits who serve him with power like flames of fire" or 2) God makes the wind and flames of fire his messengers and servants. In the original language the word for "angel" is the same as "messenger," and the word for "spirits" is the same as "wind." With either possible meaning, the point is that the angels serve the Son because he is superior. (See: [[rc://en/ta/man/jit/figs-metaphor]])