Is it true that The British Isles consist of two main islands United Kingdom and Ireland?

No, the British Isles consist of several major islands, including the islands of Great Britain, Ireland, the Isle of Man, the Channel Islands, and many smaller islands. Great Britain is the largest island in the British Isles and includes England, Scotland, and Wales. Ireland is the second-largest island in the British Isles and is divided into the Republic of Ireland and Northern Ireland.