This is the 4235th most frequent Russian word.
челябинске
"Челябинске" is the prepositional case of "Челябинск," meaning "in Chelyabinsk" (a city in Russia).
In this sentence, 'Челябинске' is in the prepositional case indicating the location where the subject lived.
Я жил в Челябинске несколько лет назад.
I lived in Chelyabinsk a few years ago.
Here, 'Челябинске' is also in the prepositional case, describing the location of a past event.
Я расскажу о событии, которое произошло в Челябинске.
I will talk about an event that happened in Chelyabinsk.
In this case, 'Челябинска' is in the genitive case, which is used after prepositions like 'из' to indicate the origin of departure.