Let's learn about a sentence from "봄날", the word "봄날" is a song name of BTS also

봄날은 간다. 벌써 여름이 온 거처럼 덥기 시작했다 :
Spring days are changing. It is already beginning to be hot as hot as summer in Korea.

봄날 : spring days <— 봄(spring) + 날(day; days)
~는,은 : a suffix makes a word subjective
간다 : (1) change; replace (2) whet (3) sharpern (4) make sharp <— 가다(go) + ㄴ(a suffix expresses present tense) + 다(a descriptive verb ending suffix)

* “~ㄴ” usage as a suffix shows present state
1) 오다(come) ==> 온다
2) 가다(go) ==> 간다
3) 먹다(eat) ==> 먹는다
4) 변하다(change) ==> 변한다

벌써 : already
여름이 : summer <— 여름(summer) + 이(a suffix makes a word subjective or the topic of conversation)
오다 : come
온 : came <— 오다 + ㄴ(a suffix makes a verb past tense or completed state)
것처럼,거처름: as like; as ~ as; as; like <—- 것,거(thing) + 처럼,같이(like; as) * 것 is right but 거 can be used for easy pronunciation)
덥다 : it is the hot weather
덥기 시작하다 : the weather begin[start] to be hot <— 덥다(be hot) + 기(a suffix makes a verb into a noun) + 시작(starting; beginning) + 하다(do, become)

* 시작[[始作] : beginning of activity <— 시(starting; be the first) + 작(do; make; rise; stand up; write; compose; start activity; profession)

<explanation of “~기” suffix>

: 흔히 ‘ㄴ˙ㅁ˙ㅅ˙ㅈ˙ㅊ˙ㅌ’ 따위 받침을 가진 어간에 붙어 사용된다 : this often is used after the root stem of a word that having last consonant like ‘ㄴ˙ㅁ˙ㅅ˙ㅈ˙ㅊ˙ㅌ’, etc

1. 자동사를 타동사로 바꾸는 구실을 함 : this changes an intranstive verb into a transitive verb

[예(ex)]
1) 숨다(hide; lurk) ==> 숨기다(make hidden; conceal)
2) 웃다(laugh) ==> 웃기다(make somebody laugh)
3) 남다(remain; be left) ==> 남기다(leave something)

2.타동사를 피동사나 사동사로 만드는 구실을 함 : this changes a transitive verb into a passive verb or a causative verb

[예(ex)]
1) 안다(embrace) ==> 안기다(be embraced; be in arms)
2) 벗다(take off; slip off; undess) ==> 벗기다(undress a person)
3) 찢다(tear down) ==> 찢기다(tear something down)

3. 용언의 어간이나 ‘이다’의 어간 또는 높임의 ‘-시-’나 시제의 ‘-았-(었)’·‘-겠-’에 붙어, 그 말을 명사형으로 만드는 전성 어미. “-ㅁ”,”~음”도 같은 역할을 함 : this make a verb or adjective a noun attached to the root stem of a word, “이다”(be), “-시-“(a letter shows respectful nuance), verb tense suffix like -았-(었)’·‘-겠-’. “-ㅁ”,”~음” also are the same.

[예(ex)]
1) 오르다(climb) ==> 오르기(climbing)
2) 잡다(grab) ==> 잡기(grabing)
3) 굵다(be thick) ==> 굵기(thickness)

4. 일부 명사 뒤에 붙어 ‘느낌’˙‘기운’ 등을 뜻함 : this shows feeling or strength/atmosphere after some noun

[예(ex)]
1) 바람기 : (1) the feel[force] of wind (2) a flirtation; fickleness; wantonness; (a) wanton temperament (3) flirtatious (4) fickle <— 바람(wind; love affair) + 기(feeling)
2) 시장기 : feeling of hunger; starve <— 시장(hunger) + 기(feeling)