This is the 107th most frequent Hungarian word.
azon
"Azon" means "that" or "on that" depending on context.
In this sentence, 'azon' is a demonstrative pronoun functioning similarly to 'that', referring to a specific evening.
Azon az estén nem mentünk sehova.
On that evening, we didn't go anywhere.
In this context, 'azon' specifies a particular provision in the law, emphasizing it's identification.
A törvényben azon rendelkezés van, ami mindenkire vonatkozik.
In the law, there is that provision which applies to everyone.
Here, 'azon' acts as a demonstrative pronoun directly emphasizing the subject of the thought process.