That's a strange thing to say. In my experience having friends in Ireland is just like having friends in any other country.
I think he means physically close. In the UK and Ireland we don't like to hug and especially don't like to kiss cheeks with our mates.
I think he means the definition of friendships can be broader or more intimate depending on the language.
He never mentioned language, he mentioned nationality though.
I just assumed he discussed nationalities with regards to regional colloquialisms. Much like you're assumed he was discussing regional social attitudes.