Ro was a Galactic Empire starfleet officer who participated in the Galactic Civil War. By the First Order's time, Ro's skills had become legendary, and the commemorative armbands worn by First Order military sergeants displayed the officer's name in Aurebesh. General Hux's monitor sported a uniform bearing the officer's name, thereby identifying her as a sergeant.
The name Ro is initially seen on a commemorative armband within the 2015 reference work titled Star Wars: The Force Awakens: The Visual Dictionary. This name appears to be an allusion to Ro, the offspring of Glyn Dillon, a costume creator who contributed to the movie Star Wars: Episode VII The Force Awakens. Likewise, "Hal," another name found on a commemorative armband, seemingly alludes to Dillon's other child, named Hal.