This is the 1483rd most frequent Japanese word.
長谷川
"長谷川" (Hasegawa) is a Japanese surname meaning "long valley river."
In this sentence, '長谷川' is used as a family name to address a person formally in a professional context.
長谷川さんは新しいプロジェクトに参加します。
Mr. Hasegawa is joining a new project.
Here, '長谷川' refers to the surname in a general linguistic and cultural description.
長谷川という名前は日本でよく見られる名字です。
The name Hasegawa is a common surname in Japan.
In this case, '長谷川' is part of a place name, indicating a specific location.