This is the 19423rd most frequent Korean word.
애플러는
"애플러는" is not a standard Korean word; it may be a typo or a name.
The term '애플러는' refers to the subject in the sentence participating in an action, implicitly highlighting the noun '애플러'.
애플러는 사과를 먹었습니다.
The applier ate an apple.
Here, '애플러는' denotes the agent performing the ongoing act of cleaning, linking the subject grammatically to the verb phrase '닦고 있는 중입니다'.
애플러는 창문을 닦고 있는 중입니다.
The applier is cleaning the window.
In this case, '애플러는' associates the subject '애플러' with the past action of traveling to the park via a bicycle, showing the narrative tense.