Chapter 15 - The Song of Moses: The Seven Last Plagues
The Angels of the Last Plagues Introduced, v. 1
The Testimony of Redeemed Jewish Christian, vv. 2-4
The Angels of the Last Plagues Make Their Appearance From the
Temple of God in Heaven, vv. 5-8
Chapter heading = The Seven Last Plagues xxx
"Sign" = symbole or figurative illistration about God’ s judgment or wrath.
Explanation is that these "fill" up the wrath of God