This is the 13004th most frequent Russian word.
луны
"Луны" means "moons" or "of the moon" in English, depending on context.
In this sentence, "луны" is used to indicate possession, showing that the light belongs to the moon.
Свет луны озарял всё вокруг.
The moonlight illuminated everything around.
Here, "луны" is used in the genitive case to specify that the phases being observed are those of the moon.
Мы наблюдали фазы луны через телескоп.
We observed the phases of the moon through a telescope.
In this example, "луны" indicates that the surface being described belongs to the moon, again showing a possessive relationship.