This is the 24th most frequent Korean word.
라고
A particle used to quote speech, indicate designation, or express intention.
In this sentence, '라고' is used as a quoting marker, indicating what was stated or introduced (that he said 'actor' to describe himself).
그는 자신을 배우라고 소개했다.
He introduced himself as an actor.
In this sentence, '라고' is used to represent quoted speech, specifying the content of the instruction.
그렇게 하라고 누가 말했니?
Who told you to do it that way?
Here '라고' is used (conjugated as '다고') to embed a quote within reported thought, expressing the speaker's perception.