It is curious that they have accepted in Korean 🇰🇷

Sentence info.

그들이 – "그들" means "they" and the subject particle "이" attaches to indicate who is doing the action.
Romanization: geudeuli

받아들인 – This is the past attributive form of the verb 받아들이다 ("to accept"). It functions as a modifier for the following noun, meaning "accepted" or "that they have accepted".
Romanization: bada-deurin

건 – A contraction of “것은” ("thing" with the topic marker 는 attached). Here it refers abstractly to "what was accepted".
Romanization: geon

신기해요 – From the adjective 신기하다 ("to be curious, amazing" or "strange") in its polite, present form. It means "is curious" or "is amazing".
Romanization: singihaeyo

Overall literal translation: "The thing that they have accepted is curious."

Tips to remember:
• Notice how the verb 받아들이다 is turned into an adjective by converting it to its past attributive form 받…인 to describe the following noun (“thing”).
• “건” comes from “것은”, so when you see 건 it is often shorthand in casual or conversational contexts.
• 신기해요 is frequently used to express wonderment, so it's a good example of how adjectives end with 해요 in a polite form.

Alternate ways to say "It is curious that they have accepted":
• 그들이 받아들인 게 신기해요. (“게” is another contraction of “것이”, commonly used in spoken Korean.)
• 그들이 받아들인 것은 신기해요. (Fully spelling out “것은” instead of contracting it.)
• 그들이 받아들였다는 게 신기해요. (Using the quote form 받아들였다는 to emphasize "that they have accepted".)

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