This is the 2338th most frequent Russian word.
набережной
"Quay" or "embankment."
Here 'набережной' is used in the instrumental case to indicate the location where the action of walking is taking place.
Мы гуляли по красивой набережной вдоль реки.
We walked along the beautiful embankment by the river.
In this sentence, 'набережной' is in the prepositional case, indicating the location of the future event.
На набережной будет проходить фестиваль летом.
A festival will take place on the embankment in the summer.
Here 'набережной' is in the instrumental case, referencing the landmark near which something is located.