Side by side; alongside — an adverb describing things or people arranged next to each other.
子供たちが並んで座って先生の話を聞いている。
The children are sitting side by side and listening to the teacher.
二人は肩を並んで歩いた。
The two walked side by side.
新商品が店の棚に並んでいる。
The new products are lined up on the store shelves.