This is the 565th most frequent Vietnamese word.
tối
"Night" or "dark."
In this sentence, "tối" is used as a noun to mean 'evening' or 'night,' referring to the time period.
Tôi sẽ đi xem phim vào tối nay.
I will go to watch a movie tonight.
Here, "tối" functions as an adjective meaning 'dark,' describing the quality of the color black.
Màu đen rất tối.
The black color is very dark.
In this context, "tối" is used to imply the action of becoming dark or less bright.