This is the 4862nd most frequent Russian word.
ирландский
"Irish" (relating to Ireland or its people, language, or culture).
In this sentence, 'ирландская' modifies 'музыка', specifying the geographical and cultural association of the music.
На празднике звучала ирландская музыка.
Irish music played at the celebration.
The word 'ирландский' functions as an adjective modifying 'язык' to indicate the language's origin.
Я изучаю ирландский язык.
I am learning the Irish language.
Here, 'ирландский' modifies 'фольклор', indicating the cultural origin.