What does 走行 mean?
走行 is a Japanese noun meaning “running a wheeled vehicle (e.g., car, traveling)” in English. It is written as 走行 in kanji, そうこう in hiragana, and soukou in romaji. This word is part of JLPT N1 vocabulary.
Example sentence
走行中の箱乗りはご遠慮下さい！
Please don't lean out of the window when we're moving.