What does Death on a Pale horse mean?

Pale Horse in American English a representation of Death, as in literature or the Bible. [after the Biblical pale horse on which Death rides, Rev. 6:8]

In some cultures, white horses stand for the balance of wisdom and power. In others, like Christianity, the white horse is a symbol of death. The horse is a universal symbol of freedom without restraint, because riding a horse made people feel they could free themselves from their own bindings.

A reference to the Four Horsemen of the Apocalypse, as the rider of a pale horse is Death.