This is the 5214th most frequent Russian word.
ночной
"Ночной" means "nocturnal" or "nighttime."
The word "ночной" in this sentence acts as an adjective describing "город" (city), indicating it is nighttime or relates to the night.
Ночной город выглядит очень красиво.
The night city looks very beautiful.
Here, "ночной" modifies "поезд" (train), indicating it is something that operates or pertains to nighttime.
Ночной поезд прибывает рано утром.
The night train arrives early in the morning.
In this case, "ночной" describes "крем" (cream), specifying its purpose or usage during the night.