the heaven... shall sing. Figure of speech Poeanismos and Prosopopoeia.
all that is therein. Compare Revelation 19:1-3.
Related Commentaries of Jeremiah 51:48
Jeremiah 51:48
48 Then the heaven and the earth, and all that is therein, shall sing for Babylon: for the spoilers shall come unto her from the north, saith the LORD.