There is no shortcuts to understanding a language. The more foreign the language is to your native language the harder it will be to learn. The only way you can understand and speak the language naturally is to have lots of experience in reading, listening and speaking.
Thankfully we live in the internet age and there is almost unlimited resources available to learn your target language. As for listening and understanding you should be exposing yourself to Korean media, whether it is movies, TV shows, panel discussions. By doing this you should naturally improve your conversation understanding ability.