You could put Jack and Kate on a New York City street and have them pass each other at rush hour on a Wednesday morning. And they would stop and turn, slowing to watch each other go by. They know each other within the context of a universal recognition. They have met before this life. And, they will meet again, in another.
Basically Jin said the same thing Hurley said. The interesting thing is that it's not a common phrase spoken by Koreans living in Seoul. According to my cousin, its something Korean "country-folk" would more likely say. This makes sense considering that Jin grew up in a semi-remote fishing village instead of Seoul. Believe it or not, Jin's like a "Korean Sawyer"