"-(으)ㄹ게" is a promise about what the speaker will do, and here it is followed by 가 or 갈게. The commonest shape is promise plus a shove: 막아줄게 가! "I'll block for you, go!", 풀어줄게 가! "we'll settle your grudge, now go!", 전화할게 가 "I'll call you, go". The other is the promise being about going itself — 갈게 갈게 "I'm coming, I'm coming", 갔다 올게 "we'll go and come back". Note that -(으)ㄹ게 only ever commits the speaker; it cannot ask anything of the listener.