The ideogram BU in Japanese, WU in Chinese, MOO (MU) in Korean, VO in Vietnamese...
means "Martial" or "War". You find it in the words Bushido, Budo, Wushu,
Vodao... An etymology study, sometimes controversial but at least
meaningful, used to say that it is the combination of two keys meaning
"to stop" - "the spear, the weapon".
famous sentence means to be both cultured in knowledge and effective in
martial arts. Often the ideas of Wen/Bun/Mun (literary, knowledge
/ exterior beauty) and Wu/Bu/Mu (martial / interior essence) seems contrary
-- mostly in our western countries. And yet, the eastern use often associate
those charatcers. In Chinese, refinement, elegance can be felt from this
combination. In Japanese, you can find the notion of uruwashii,
"balance and harmony between exterior beauty and deep essence" e.g. found
in the classical Heike Monogatari. This expression is a good summary
of the purpose of every Martial Artists, isn't it ?