(으)ㄹ 거예요: Future tense, will, going to

Where 거예요 comes from

(으)ㄹ 거예요 is three pieces put together. (으)ㄹ is the future modifier, 거 geo is the spoken form of 것 geot, "thing", and 예요 yeyo is "it is". So 갈 거예요 gal geoyeyo is built a bit like "it's a going-to-go thing".

That's also why you'll see two longer versions. In books and the news it's written (으)ㄹ 것이다 (eu)l geosida, and in formal speech it's (으)ㄹ 겁니다 (eu)l geomnida, short for (으)ㄹ 것입니다.

거에요 or 거예요?

It's always 거예요. 거 ends in a vowel, and after a vowel 이에요 becomes 예요, the same way you say 의사예요 uisayeyo, "I'm a doctor". 거에요 is one of the most common spelling mistakes online, even among Koreans, because the two sound almost the same.

How it sounds

After the ㄹ, the ㄱ of 거 is said hard, so 갈 거예요 sounds like [갈 꺼예요]. The 예 is often said like 에, too, which is where the 거에요 spelling comes from.

(으)ㄹ 거예요, (으)ㄹ게요 or 겠?

All three can talk about the future, but they aren't the same:

• (으)ㄹ 거예요 is the everyday way to say plans and predictions, about anyone: 내일 친구를 만날 거예요 naeil chingureul mannal geoyeyo, "I'm going to meet a friend tomorrow".
• (으)ㄹ게요** is only about yourself, and it's a promise or an offer to the person you're talking to: 제가 할게요 jega halgeyo, "I'll do it".
• 겠** sounds more decided and a little formal when it's about you, and when it's a guess, it reacts to something right in front of you: 맛있겠다 masitgetda, "that looks good".