This is the 7916th most frequent Russian word.
килиан
"Килиан" is a transliteration of the name "Kilian" or "Cillian," often used as a given name of Irish origin.
In this sentence, 'Килиан' serves as a proper noun - a personal name used as the subject of the verb.
Килиан приехал в Москву на конференцию.
Kilian arrived in Moscow for a conference.
Here, 'Килиана' is the genitive case of the proper noun 'Килиан', indicating possession or relation.
Сегодня мы обсуждали карьеру Килиана.
Today we discussed Kilian's career.
This time, 'Килиан' is in the nominative case, representing the direct reference to a person.