rainbow

This is the multicolored arc of light that often appears in the sky after a rainstorm.

a sign

A sign is something (such as an object or event) that gives a certain meaning or which points to something that is true or will happen.

In some languages, it may be better to say: “to show that he had promised.”

Make sure it is clear that this means every time a rainbow appeared from that time on. It may be necessary to add: “From then on, every time…”

This refers back to the previous frame in which God promised to never again destroy the earth with a flood.

These references may be slightly different in some Bible translations.