This is the 622nd most frequent Korean word.
기자회견을
"Press conference."
Here, '기자회견을' (press conference) is used as an event through which the subject (the president) performs an action (announcement).
대통령이 기자회견을 통해 정책을 발표했다.
The president announced policies through the press conference.
In this sentence, '기자회견을' (press conference) is the object of the preparation described in the process.
기자회견을 준비하는 과정이 길었다.
The process of preparing for the press conference was long.
Here, '기자회견을' (press conference) is the event that was completed by the subject before performing the next action.