This is the 13603rd most frequent Turkish word.
kuralların
"Kuralların" means "of the rules" in English.
In this sentence, "kuralların" is the possessive form (genitive case) of "kurallar" (rules), used to describe whose purpose is being referred to (i.e., the purpose of rules).
Kuralların amacı herkesin uyum içinde yaşamasını sağlamaktır.
The purpose of rules is to ensure everyone lives in harmony.
Here, "kuralların" again is in the possessive form, indicating whose boundaries one might exceed (i.e., the boundaries of the rules).
Eğer kuralların dışına çıkarsan, sorunlar yaşayabilirsin.
If you go beyond the rules, you might face issues.
In this instance, "kuralların" is showing possession related to a topic being discussed (i.e., the importance of rules), aligning with its genitive grammatical usage.