what western countries that their main language is english?

Gibraltar, Guernsey, Isle of Man, Jersey, Malta (official language).

Ireland is the only European country besides the UK that has English as the main language.

Edit: I'm Irish too, I know that Irish is the first official language. But English is the main everyday language for the majority of people here.

Gibraltar, Malta maybe and Cyprus maybe (but lots of Greek and Turkish). English is spoken very widely in Scandinavia and Germany and in fact in many European countries other than France. Also much of Africa is English-speaking and a number of Asian countries speak it; there are reckoned to be 400,000,000 learners of English in mainland China alone. (Then there's most of northern America.) English is also an official language in some surprising places like Libya and Mozambique.

By the way, your question would be better phrased: "Which European countries' main language is English?"

tzddean- Gaeilge is the offical first language of Eire.

Most other European nations have a degree of English, but it is not their main language.