Belarus has long, platinum blonde hair and dark blue eyes.
She is an intimidating, harsh young woman who has a deep infatuation with her older brother Russia, to the point where she wants to get married to him. However, he doesn't feel the same way, and feels disturbed by her very presence.
Belarus is shown to carry around a knife at points, most notably in the "Meeting Of The World" strip where she's holding it to a traumatized Latvia's back as her brother scares him.
According to a footnote at the end of 'Russia's Bis And Little Sisters', Belarus briefly became a sort of adoptive younger sister to America after the fall of the Soviet Union.