Refers to the United Kingdom of Great Britain and Northern Ireland. In everyday Japanese, イギリス is the standard name for the UK.
from Portuguese inglês
イギリスはヨーロッパの北西に位置する島国です。
The United Kingdom is an island nation located in northwestern Europe.
I plan to study abroad in the UK next year.
Colloquially, イギリス is sometimes used to mean England specifically, though technically England is イングランド.
When you say 'イギリス', many people think of London and Big Ben.