This is the 4862nd most frequent Russian word.
ирландский
"Irish" (relating to Ireland or its people, language, or culture).
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.
Ирландский фольклор очень богат.
Irish folklore is very rich.
In this sentence, 'ирландская' modifies 'музыка', specifying the geographical and cultural association of the music.