"Sori ha,korean k pala!" is a contracted way of saying "Sorry ha, Korean ka pala". If it is not used with other enclitic markers, "pala" (stress on the second syllable) means "I didn't know, I just learned". "Korean ka" means "You are Korean" so "Korean ka pala" means something like "I didn't know you were Korean". Kumain ka na. You already ate. Kumain ka na pala. So you already ate [I didn't know that] ... I didn't know you already ate [I shouldn't have prepared this dinner for two].