This is the 3394th most frequent Japanese word.
歩行
"歩行" means "walking" or "walking motion."
In this sentence, '歩行' refers to the action of walking, emphasizing it as an activity.
歩行は健康に良い運動です。
Walking is a beneficial exercise for health.
Here '歩行' is used to indicate the purpose of the path—it's exclusively for people to walk, not for vehicles.
この道は歩行専用ですので、車両は通行できません。
This path is for walking only, so vehicles cannot pass through.
Here, '歩行' is used within the word '歩行者' (pedestrian), indicating individuals who walk.