This is the 127th most frequent French word.
rien
"Rien" means "nothing" in English.
In this sentence, 'rien' is used with a negative construction to mean 'nothing', portraying an absence of anything visible.
Je ne vois rien.
I see nothing.
In this case, 'rien' acts as the subject of the sentence, emphasizing that no obstacle is insurmountable.
Rien n'est impossible.
Nothing is impossible.
Here, 'rien' complements the verb phrase by indicating that the subject has spoken about no particular topic.