This is the 6386th most frequent Korean word.
알렉산더
Alexander (a proper noun, typically a name).
This context shows '알렉산더' as a personal name and the subject (doing the action of going).
알렉산더는 오늘 학교에 갔어요.
Alexander went to school today.
Here, '알렉산더' is part of a title, illustrating its use as a historical figure's name.
이 책은 알렉산더 대왕에 관한 이야기입니다.
This book is about Alexander the Great.
In this sentence, '알렉산더' is the object of the action, showing its use in a desire to interact with the person.