This is the 9290th most frequent Japanese word.
白井
"白井" is a Japanese surname meaning "white well."
The word '白井' is used as a proper noun referring to a person's surname.
白井さんは新しいプロジェクトを担当しています。
Mr. Shirai is in charge of the new project.
Here, '白井' is used as a proper noun representing a geographic location.
白井という地名がこの地域にあります。
There is a place name Shirai in this region.
In this case, '白井' is used as a character or entity name in a fictive work.