The particle 의 denotes possession. For example, the sentence 민지의 친구가 학생입니다 shows that Minji is doind the possessing. (민지 = Minji. 의 = possessive particle. 친구 = friend. 가 = subject marking particle. 학생 = student. 입니다 = copula ending in deferential polite form, in this sentence means ‘is’.) In English this sentence would mean, ‘Minji’s friend is a student’. (In Korean there are no indefinite or definite articles. The ‘a’ in the sentence is implied because there would otherwise be a plural marker attached to 친구 if the sentence were to mean ‘friends’ instead of ‘friend’.)

The possessor does not have to be human. You could say, 소라는 시험의 내용을 압니다. (소라 = Sora. 시험 = exam. 내용 = content. 을 = object marking particle. 압니다 = the verb ‘know’ in the deferential polite form, 알다 is the infinitive form.) In English, the sentence would mean, ‘Sora knows [about] the contents of the exam’. I inserted the word ‘about’ because if you translate the sentence literally, there is no word for ‘about’ in the sentence. This just shows how English and Korean are two different languages. Sometimes to the point where they don’t reconcile in translation in perfect harmony.

When you’re talking about yourself and the possessor, there’s a shortcut when a possessive particle is attached to the pronoun ‘I’. For example when you want to use the polite form of “I” with the possessive particle, you’re going to get 제. 제 이야기가 길어요. (제 = my. 이야기 = story. 가 = subject marking particle. 길어요 = verb ‘long’ in the standard polite form, 길다 is the infinitive form of the verb ‘to be long’. In English this sentence means, ‘My story is long’. Originally the polite term for ‘I’ was 저. However, when you add a possessive particle, Korean people shorten it to 제 instead of saying it as 저의.

When you’re using ‘I’ in the humble form with the possessive particle, it’s going to be 내. The humble word for ‘I’ without the possessive particle is 나. However, instead of saying the word ‘my’ as 나의 the word is abbreviated as 내. Take a look at a sentence like this, 아! 내 가방! (아! = Ah!/Oh! showing surprise. 내 = ‘my’ plain form. 가방 = bag.) In English this sentence would mean, ‘Ah! My bag’. I would use the polite ‘I’ in formal situations and the humble ‘I’ in informal situations. As for both the polite and humble forms for ‘I’, I would just memorize the contracted forms because they are used very often.