What does Daniel 3:5 mean?
Babylon effectively ruled over the entire ancient middle east—the king's commands in this passage emphasize this fact. Nebuchadnezzar's dream (Daniel 2:1–3) apparently inspired him to create a large golden idol (Daniel 2:36–38; 3:1). He commanded officials from all over the empire to attend a dedication (Daniel 3:2–3). His command, contained here, was delivered in both poetic and literal terms to every person in the entire kingdom (Daniel 3:4).Throughout history music has been used to stir emotions and bring about a desired response. Here, the meaning of the long list of musical objects is more symbolic than literal. This passage in Daniel notably repeats several phrases—including four copies of the same list of instruments (Daniel 3:5, 7, 10, 15). This evokes the legalistic, oppressive nature of the king's commands. The wide variety of instruments also implies the large reach of the Babylonian Empire.
To "fall down" in this context means to kneel or lay face down in an expression of humility. When the people hear "every kind of music," as a cue, they are to worship this idol commissioned by Nebuchadnezzar.