Let's learn about the usage of “이제 알겠어요”(I get it now)

당신이 왜 그렇게 말했는지 이제야 알겠어요.

1) Now i understand you.
2) I see that now.
3) Now i know what you said.
4) Now i know why you said that.
5) Now i know where you got it.
6) I know what you mean now.

<Dialogue of the above>

<A person> 요전 날 행동에 대해 정말로[진심으로] 사과드려요. 이제야 당신이 왜 그렇게 말했는지 알겠어요. I do apologise for my behaviour the other day. I now know why you sait that to me.

<B person> 괜챦아요, 모든 게 잘되어서 기뻐요. Well, I ‘m glad that things are settled then.

<Detail Explanation of the above>

당신이 : you <— 당신(you) + 이(a suffix makes a word subjective after last consonant of a word)
왜 : why
그렇다 : be such
그렇게 : such; like that; as that <— 그렇다 + 게(a suffix makes a verb adverb)
말하다 : say; tell; speak
말했다 : said <— 말하다 + 었/았(a suffix makes a verb past tense) + 다(a verb ending suffix)
말했는지 알겠다 : i understand what you said <— 말했다 + 는(a suffix, which located after last consonant,  connect a verb with a noun) + 지(this means “거” or “것”(thing or what”) + 를/을(a suffix makes a word objective; but this omitted) + 알다(know) + 겠(a guess suffix) + 다(a verb ending suffix)
알겠어요 : i say to you that i understand what ... <— 알겠다 + 어/아( a descriptive suffix notify my idea or thinking) + 요(a winsome suffix)
요전 날 : the other day <— 요(here, the; this is contracted from “여기”(here; the) + 전(before) + 날(day)
행동[行動] : action; an act; conduct; behavior; 『군[軍](military)』 operations
~에 대해, ~에 대하여 : about, with related with; according to <— 에(a time or place suffix) + 대[對]하다(deal with) + 여(a suffix makes a verb adverb)
* “~에 대해” is a short form of “~에 대하여”
정말 : truth(=거짓에 대해 진실; truth against falsy); a fact(=사실); reality(=현실)
정말로 : [=참으로] truly; really; indeed; [=확실히] certainly; assuredly; surely; to be sure; [=마음속으로부터] heartily; sincerely; [=매우] very; quite; greatly <— 정말 + 로/으로(a suffix makes a noun adverb)
진심[[眞心] : sincerity; earnestness; seriousness; a true heart
진심으로 : heartily, cordially <— 진심 + 으로/로(a suffix makes a noun adverb)
사과[[謝過] : an apology
사과하다 : apologize
드리다 : a honourific form or “주다,준다”(give)
사고드리다 : a honourific form of “사과하다”
사과드려요 : apologize (with honoirific nuance) <— 사과드리다 + 어/아(a desxriptive suffix notify my idea or thinking or mind) + 요(a winsome suffix)

괜챦다 : (1) [=쓸 만하다] nice; good; not so bad; passable; fair; fine. (2) [=무방하다] may; can; be allowed to ; be justified in ; justifiable; warrantable; all right; O.K.; will do. (3) [=안심이다] safe; secure; free from danger; all right
괜챦아요 : all right; well <— 괜챦다 + 어/아(a desxriptive suffix notify my idea or thinking or mind) + 요(a winsome suffix)
모든 게, 모든 것이 : everything; all things <— 모든(all; every) + 것이,게(thing)
* “게” is a short form of “것”(thing) + “이”(a suffix makes a word subjective or the topic of concersation)
잘 : well
되다 : become
잘되다 : (1) [=성공하다] get on in the world[in life]; rise[succeed] in the world; make a success in life[the world]; make one's way[get on] in life; [=승진하다] win[get / obtain] promotion. (2) [일이(a task; a thing)] go well[right]; work well; work out; go on smoothly; [결과가(a result)] come[turn] out all right; pay off.
기쁘다 : be joyful
잘되어서 기뻐요 : i am glad that things are settled <— 잘되다(go well) + 어서(an ending suffix indicate that the word will be the condition, means, reason, etc of the following words) + 기쁘다 + 어/아(a desxriptive suffix notify my idea or thinking or mind) + 요(a winsome suffix)