Learn Hardcore Korean: gabang aneneun yeonpilgwa chaegi isseoyo. - Inside the bag, there are pencils and books.

가방에 indicates a general location (“at/in the bag”) but doesn’t specify being inside. 가방 안에 explicitly means “inside the bag.” Adding the topic marker 는 (→ 안에는) marks “inside the bag” as the topic—“as for what’s inside the bag”—so you can then talk about what’s there.

What role does 있어요 play here?

있어요 is the polite-present form of the verb 있다, meaning “to exist” or “to have.” When used with a location (에/안에), it means “there is/are.” So 가방 안에는 연필과 책이 있어요. literally means “Inside the bag, pencils and books exist”—i.e. “There are pencils and books in the bag.”

Why is it 연필과 책 instead of 연필와 책?

The conjunction 와/과 means “and.” Use 과 after consonant-ending nouns (연필 ends in ㄹ) and 와 after vowel-ending nouns (사과 ends in ㅏ). Hence 연필과 책 (“pencils and books”).

Where is the subject marker 이/가 in 연필과 책이 있어요?

When listing multiple nouns, you attach 이/가 only to the last noun in the list—연필과 책이—and it covers the whole list. In casual speech, the final -이 may sound reduced, but it’s still there on 책이.

Can I say 연필과 책은 가방 안에 있어요 instead?

Yes. That just shifts the topic. 연필과 책은 means “as for the pencils and books,” so you’re emphasizing the items rather than the container. Both word orders are correct; the nuance changes slightly.

What’s the difference between 있어요 and 있습니다?

They’re both present-tense forms of 있다 at different politeness levels. 있어요 is polite-informal (–요 form) used in daily conversation. 있습니다 is polite-formal, used in formal speeches or writing. The meaning “there is/are” remains the same.

Can I use 연필하고 책 instead of 연필과 책?

Yes. 하고 is a casual conjunction meaning “and” that works after both consonant- and vowel-ending nouns. So 가방 안에는 연필하고 책이 있어요 is perfectly natural in spoken Korean.