The house (or people) directly across the street; the neighbor who lives opposite your house.
お向かいのおばさんが毎朝犬の散歩をしています。
The lady across the street walks her dog every morning.
引っ越してきたら、お向かいに挨拶に行ったほうがいいですよ。
When you move in, it's a good idea to go and greet the people across the street.
お向かいの家は子どもが多くて、夏は賑やかだ。
The house across the street has many children, so it's lively in summer.
窓から見えるお向かいの屋根に雪が積もっている。
There is snow piled on the roof of the house across the street that I can see from the window.