This is the 257th most frequent Korean word.
이란
The Korean word "이란" means "called," "is," or "refers to," depending on the context.
Here, '이란' introduces a conceptual explanation or definition of 'happiness'.
행복이란 노력 없이는 얻을 수 없는 것입니다.
Happiness is something that cannot be achieved without effort.
In this sentence, '이란' refers to the country Iran in a straightforward nominative form.
이란은 중동에 위치한 국가입니다.
Iran is a country located in the Middle East.
In this usage, '이란' is used to introduce and define what science is.