While Bela does mean white, Rus is a different geographical and political term than Russia.

Rus, also known as Ruthenia, refers to the Eastern Slavic lands that nowadays belong mostly to Belarus and Ukraine. In the modern Belarusian language there is a clear distinction between ruski (referring to Ruthenia) and rasiejski (referring to Russia).

The word Rus appeared in Eastern Europe with the advance of Scandinavians to the south. In the 10th century the word Rus described Scandinavian newcomers as distinct from the Slavs. When a number of Slavic tribes had been conquered by Scandinavians, they adopted the names of their victors.  

See the historical map of Rus in 882-1240.