Let me try "to be."
There are 2 words in Korean that translate as "to be." However; don't confuse them with "Estar" and "Ser." they have different meanings.
이다 is the infinitive version of the word that indicates a state of being.
있다 is the infinitive version of the word that indicates existence, or existence in a place.
To say "I am a Korean man," I would say "나는 한국 사람 입니다." (입니다 is the formal, present tense version of 이다.
To say "I am home," you would say "나는 집에 있읍니다." (있읍니다 being formal present tense of 있다).
Are you familiar with formal, polite, and informal verb endings in Korean? If not, then these are a good place to start on conjugation.