naneun doseogwaneseo soseolchaegeul billyeosseo.

• 나 is the informal pronoun “I.”
• -는 is the topic marker.
  Put together, 나는 literally means “As for me,” marking “I” as the topic of the sentence.

• 도서관 means “library.”
• -에서 indicates the place where an action happens (“at,” “in,” or “from”).
  So 도서관에서 = “at the library (where the borrowing took place).”
• In contrast, -에 marks a destination or location of existence (“to/in”), not the site of an action.

• 소설책 = “novel book” (i.e. “a novel”).
• -을 is the direct object particle, marking what is being acted upon.
  Thus 소설책을 means “(the) novel” as the thing you borrowed.

• 빌리다 is the dictionary form, meaning “to borrow.”
• 빌렸어 is the informal, past-tense, declarative form, so it means “(I) borrowed.”

1. Take the verb stem 빌리-.
2. Add the past-tense marker -었-, giving 빌리 + 었 → 빌렸 (리 + 었 contracts to 렸).
3. Add the informal ending -어, resulting in 빌렸 + 어 = 빌렸어.

• 빌리다 means “to borrow” (you receive something from someone).
• The opposite, “to lend,” is 빌려주다 (빌려 + 주다 = “to lend to someone”).

Korean uses a Subject-Object-Verb (SOV) word order. In other words, the verb always comes last:
Subject/Topic → (Location) → Object → Verb.
Hence 나는 도서관에서 소설책을 빌렸어 follows that pattern.

• -는 (as in 나는) introduces or highlights the topic, often implying contrast or general background.
• -가 focuses on the grammatical subject, usually presenting new or emphasized information.
  In this sentence, using -는 makes “I” the topic (“As for me…”) rather than merely marking “I” as the subject.