The three most common and important verbs in English are be, have and do, and in Korean 이다 (i-da), 있다 (itt-da) and 하다 (ha-da) (in all their forms). As main verbs, these cover much the same meanings, but divide up those meanings in different ways. 이다 is narrower in usage than be, and 있다 and 하다 wider than have and do respectively. In particular, 하다 takes on meanings represented by English be and have, and also many main verbs.
English – Korean – literal translation
I am happy. – 나는 행복해요. – I happiness do.
I am Australian/an English teacher. – 나는 호주사람/영어선생님 이에요.- I Australia person/English teacher am.
I am here/in South Korea. – 나는 여기/한국에 있어요. – I here/South Korea-in exist.
There is a shower in my apartment. – 내 아파트에 샤워가 있어요. – My apartment-in shower exists.
I have (possess) a shower in my apartment. – 나는 내 아파트에 샤워가 있어요. – For me, my apartment-in shower exists.
I have (take) a shower in my apartment. – 나는 아파트에 샤워 해요. – I my apartment-in shower do.
I exercise/do exercise. – 나는 운덩 해요. – I exercise do.
I go shopping. I do the shopping. – 나는 쇼핑 해요. – I shopping do.
I study. – 나는 공부 해요. – I study do.
Be and have are also auxiliary verbs (be for continuous aspect and passive voice, and have for perfect aspect); these either don’t exist (or I haven’t encountered them yet) or are made very differently in Korean.