Although we call it a subject, its position is not for subjects, the actor, only. A topic can also be in the position. A topic may not be an actor, but the one which the sentence is about. Let's take an example: You bumped into a friend after lunch. Your friend asks you, "Hey, how about a lunch?" You might want to say, "Lunch? I already had it. How about a cup of coffee?" The first part of this speech can be understood, 'As for (or, speaking of) lunch, I already ate it.' In Korean, this can be stated simply