What is the meaning of Ngày?

day

date

daytime

a day (period of 24 hours; period from midnight to the following midnight; rotational period of a planet; part of a day period which one spends at one's job, school, etc.)

day (period between sunrise and sunset)

a date (that which specifies the time of writing, inscription etc.; point of time at which a transaction or event takes place)

Source: wiktionary.org