This is the 4024th most frequent Russian word.
луганске
"Луганске" is the prepositional case of "Луганск," which refers to the city of Luhansk in eastern Ukraine.
Here, 'Луганске' is used as the locative case of 'Луганск', indicating the place where something is or occurs.
Я был в Луганске прошлым летом.
I was in Luhansk last summer.
In this instance, 'Луганске' remains in the locative case, describing the location of various attractions.
В Луганске много интересных достопримечательностей.
There are many interesting attractions in Luhansk.
Similarly here, 'Луганске' is used in the locative case, stating where the meeting took place.