1)"Some of An Garda Síochána’s core functions include:...."
Why is it "Some of An Garda......" not "Some of the Garda......"?
2)"An Garda Síochána is the national police service of Ireland. The Mission of An Garda Síochána is Working with Communities to Protect and Serve."
The question is about the use of the indefenite article.
In Gaelic "an" is "the" singular. "An Garda Síochána" is Gaelic for "The Guardians (of the) Peace" literally translated. Usually we translate it as "The Police".
"An Garda" singular. "Na Gardai" plural. Remember we are talking about the Irish language not the English language, they are totally different.