Welcome to reason 6000 that I love the Korean language. This grammatical principle adds a chunk of extra meaning to a sentence in just one syllable.
What it means:
There are a couple of plain, un-nuanced ways to speak about something that will happen in the future in Korean. This principle, however, is not plain, and can really soften your sentences and make you sound like a very considerate person.
By using -ㄹ게 / -을게, you add a nuance of checking to make sure the action you’re going to take is okay with the person to whom you’re speaking. Basically, you’re informing them of your intention to do something, and giving them a chance to speak up and say they’d rather you didn’t.
In essence, it turns a sentence like, “I’m going to take this call.” into the softer, more considerate sentence, “I’m going to take this call, if you don’t mind.” This creates a situation where the other person could reply, “Actually, could you just let it go to voicemail?” without them being the bad guy and you getting offended. Pretty cool, isn’t it?
There is one limitation with this particle. It can only be used to speak about one’s own future actions. The regular future tense endings -ㄹ 거야 / -을 거야 and -겠어 can be used to speak about other people or about oneself. For example, “He will go to the store.”, “My mom will buy a house.”, “I will call you next week.” etc. But -ㄹ게 / -을게 can only be used to speak about one’s own intention to do something. You can’t use it to say, “He’ll just run to the washroom, if that’s okay with you.” It always means “I will do X, if that’s okay with you.”
How to attach it:
Attach this particle to the root of the verb. Remember, all verbs end in 다. Drop 다 and you’re left with the root.
If the root ends in a vowel, attach ㄹ to the end of that vowel and follow it with 게.
Eg: 말하다 = to speak. 말하다 – 다 + ㄹ게 = 말할게
If the root ends in a consonant, attach 을게.
Eg: 잡다 = to grab, to hold. 잡다 – 다 + 을게 = 잡을게
To increase the formality/respect, add 요 onto the end. Eg: 말할게요, 잡을게요
I won’t translate these with the nuance spelled out, but note that you can essentially add “if that’s okay with you”, “if you don’t mind”, “unless you object” etc, to the end of each of these sentences.
Snow Flower by V:
세상을 네게 줄게 ~ “I’ll give you the world.”
Original verb: 주다 – to give
널 데려갈게 완전히 새로운 세상에 ~ “I’ll take you to a completely new world.”
Original verb: 데려가다 – to take someone [somewhere]
네 주위를 맴돌게. 네 곁에 있어 줄게. 네 빛이 되어 줄게. ~ “I’ll revolve around you. I’ll stay by your side. I’ll become your light.”
맴돌다 – to spin in place, to revolve
있다 – to be present
되다 – to become
*Note: the 2nd and 3 verbs have this principle applied, and then -ㄹ게 applied onto that.
이젠 너의 손을 놓을게 ~ “I’m going to let go of your hand now.”
Original verb: 놓다 – to let go of, to put down
등골브레이커 (Spine Breaker):
그래 말리진 않을게 ~ “Fine, I won’t stop you.”
Original particle: 않다 – to not do X