The official language is Irish Gaelic and spoken in most areas as the first language. English is the other official language spoken.
Greenwich Mean Time
You can visit Ireland at any time of year, but if you want to avoid the cold winter months, that might be better - so you can fully appreciate the countryside walks and coastline. Peak tourist season, unsurprisingly, is July and August, so try to go either side of those months. June or September would be the best months - however, if you want to check out the art scene, October hosts a lot of art festivals across Ireland.