This is the 9579th most frequent Korean word.
경찰관은
"Police officer."
In this sentence, '경찰관은' refers to police officers in general, discussing an ideal characteristic expected of the profession.
경찰관은 정직해야 한다.
Police officers must be honest.
In this sentence, the word '경찰관은' functions as the subject, indicating who performed the action of catching.
경찰관은 범인을 잡았다.
The police officer caught the criminal.
Here, '경찰관은' is used to emphasize the role of the police officer as responsible for citizen safety.