에서 is a suffix that is a variation on the locative particle 에. It indicates the place where an action is taking place. In the case of verbs of movement it indicates where the person started from. It is similar to the Japanese particles で and から.

• 부산에서 놀았어요 I had fun in Busan.
• 수영장에서 수영했어요 I swam in the swimming pool.
• 민속촌에서 구경했어요 I went sightseeing in the folk village.