What does a rainbow
Meaning of colors
The rainbow colors red, purple (which is a mix of red and blue), and scarlet (a bright red) and crimson (a cooler hue of the color red) were used extensively in the tabernacle Moses made in the wilderness. They were also a part of the temple later constructed, and in the garments for the High Priest and other priests (Exodus 25:3-5, 36:8, 19, 27:16, 28:4-8, 39:1-2, etc.). These colors were types or shadows of atonement.
The colors purple and scarlet can mean or represent iniquity or sinfulness (Revelation 17:3-4, 18:16, etc.). Purple itself was used as a symbol of royalty (Judges 8:26). Scarlet by itself can represent prosperity (Proverbs 31:21, Lamentations 4:5).
The color blue, referred to directly or when scripture states something is like the appearance of a sapphire or sapphire stone, can be a symbol of deity or royalty (Numbers 4:5-12; Ezekiel 1:26, Esther 8:15, etc.). Blue was also the color God commanded some threads in the fringes of Israelite garments be colored in order to remind them of the commandments and living a godly way of life (Numbers 15:38 - 39).
The color white found in a rainbow can mean holiness, righteousness and dedication to serving the true God (Leviticus 16:4, 2Chronicles 5:12, etc.). In vision, Jesus first appears to the apostle John with hair that is white (Revelation 1:12 - 14). All believers throughout history who die in the faith will, according to the Bible, be resurrected and given white robes to wear (Revelation 7:13 - 14, 19:7 - 8).