This word means “just, right”, and is used to emphasize the place and time expressions.
It plays the role as an adjunct with the meaning of doing something immediately, without delay.
Eg.
Nhận được tin anh ấy đi ngay.
(He went immediately when receiving the news.)
Im ngay! (Keep silent. Please!)
In addition, it is used as a subjunctive to emphasize the determination of a location, time, and place at the time when the speaker says.
Eg.
Ho sống ngay trong thành phố.
(They do live in the city.)
It also emphasizes the level of something, including the case being mentioned.
Eg.
Nó đối xử tệ ngay cả với mẹ nó.
(He treats everybody badly, even his mother.)