This is the 1632nd most frequent Japanese word.
沿い
"Along" or "alongside."
In this sentence, '沿い' means 'along' referring to the alignment or adjacency to the river.
川沿いに桜が咲き誇っています。
Cherry blossoms are in full bloom along the river.
Here, '沿い' indicates 'along' pertaining to the street that runs adjacent to the station.
駅沿いの商店街には多くの人が訪れます。
Many people visit the shopping street along the station.
In this sentence, '沿い' refers to being aligned or situated adjacent to the highway.