What are the colors and symbols of the twelve tribes' flags?

Answer:¹

Each of the 12 tribes had its own corresponding flag with its symbol emblazoned upon the flag. The flag's color paralleled the color of that tribe's stone in the High Priest's breastplate (choshen). In most cases, the flag's symbol corresponded to the blessing given that tribe by Jacob before his passing and/or that tribe's spiritual service.

They are as follows:

Reuven: Red flag with mandrake flowers (duda'im)

Shimon: Green flag with buildings of the city of Shchem

Levi: Red, white and black flag with the High Priest's breastplate (Urim v'Tumim)

Yehudah: Sky blue flag with a lion

Yisasschar: Bluish black flag with a sun and moon

Zevulun: White flag with a ship

Dan: Blue flag with a snake

Naftali: Deep wine colored flag with a deer

Gad: Black and white flag with a tent camp

Asher: Pearlescent colored flag with a tree

Yosef: Pitch black flag with Egypt depicted upon it. It also had two parts for Yosef's two sons who became tribes: For his son Ephraim was pictured a flag with an ox, and for Menasheh was a flag with a wild ox

Binyamin: Multicolored flag with a wolf

You may also want to read about "Which precious stones were set in the High Priest's breastplate?"