"Kerberos" is a computer network authentication protocol and "krb5-locales" are the settings related to internationalization. Or as explained in the link:
Internationalization support for MIT Kerberos
Kerberos is a system for authenticating users and services on a network.
Kerberos is a trusted third-party service. That means that there is a
third party (the Kerberos server) that is trusted by all the entities on
the network (users and services, usually called "principals").
This is the MIT reference implementation of Kerberos V5.
This package contains internationalized messages for MIT Kerberos.
So ... any text used in "kerberos" is stored in "krb5-locales" and based on you language settings it will pick up the translation for your language (if available).
It is 3rd party software so I assume translation are done by them.