Learn Hardcore Korean: geureonde i munjangui uimiga jal ihaedoeji anhayo. - However, I don’t quite understand the meaning of this sentence.

그런데 is a conjunction meaning “but,” “however,” or “by the way.” It introduces a contrast or a new topic related to what was said before. In 그런데 이 문장의 의미가 잘 이해되지 않아요, it signals that although something was explained or shown earlier, the speaker still can’t grasp the meaning.

Why is 이 attached to 문장, and what does it indicate?

이 is the subject particle used after a noun ending in a consonant. It marks 문장 (“sentence”) as the subject of the clause. So 이 문장 means “this sentence,” with 이 functioning like “this” plus the particle.

Why does 의미 take the particle -가 instead of -은/는?

Particles -가 and -는 both mark subjects, but -가 often introduces new or indefinite information. Here, 의미가 잘 이해되지 않아요 states a fact: “the meaning is not well understood.” Using -가 keeps the focus on the meaning as the grammatical subject of 이해되지 않다.

What does 잘 do in this sentence, and where does it belong?

잘 is an adverb meaning “well.” It modifies the verb phrase 이해되지 않아요, indicating the degree of understanding. Placing 잘 right before the verb is the standard word order in Korean for adverbs.

Why is the verb 이해되다 used instead of 이해하다, and what’s the nuance?

이해하다 is the active verb “to understand,” meaning “I understand something.” 이해되다 is its passive/intransitive counterpart, “to be understood,” which emphasizes that the subject (the meaning) isn’t coming through clearly to the speaker. Here, the speaker doesn’t actively fail to understand; rather, the sentence’s meaning “won’t be understood.”

What is the difference between negating with 안 before a verb and using -지 않아요 after it?

Both negate a verb, but

안 + verb is the simple form (e.g., 안 이해돼요).
Verb stem + -지 않아요 is slightly more formal/polite (e.g., 이해되지 않아요).
In many contexts they’re interchangeable, but -지 않아요 often sounds a bit more neutral or soft.

What level of politeness does the ending -요 convey, and how could you change it?

The -요 ending marks polite informal speech (called “해요체”). To make it more casual, you could drop -요 (그런데 이 문장의 의미가 잘 이해되지 않아). To be more formally polite, use 습니다 form (그런데 이 문장의 의미가 잘 이해되지 않습니다).