은/는 - use these two to Show spicificly what the topic of the scentence is about 애비는 나의 찬구- ABBY is my friend ~ we emphisise Abby 애비 나의 잔구- Abby is my friend ~ We don't emphisize anything You can use 는 to say explain more firmly; so if someone says you don't have friends you can say the first phrase as an assurence because abby is. 를/을 - Like a Link word Linking the noun spicificly to the verb.. example 사과를 싶어요- I want an apple- you may use 를 to show you don't want a pear or pinapple but an apple 의- use this like as like MYNE haha so you say 나의 사과. MY apple. Understand? Oah and we have the 2 forms so that you can add it to a noun ending in consonant / vowel, if it ends in a constonant you use 은 or 을 however ending in a vowel you will use 는 or 를 Hope i helped c:

There is a bit simple rules here. 은 : 나은(X) 너은(X) 그은(X) 김은(O) 밥은(O) 성은(O) Do you notice something? Just before '은', there must be 'ba-chim' or 'the last(final) consonant' (ㄴ/ㅂ/o in those examples). 의 : 너의/나의/집의/밥의/그의...there is no strict rule for '의' and its meaning is '~of ~' or sometimes it refers directions as well. But it will be too complicating to explain all, so I'll stop. 책상(desk)'의' 의미(meaning) = meaning of the desk 는 : 나는/너는 (O) but 집는(X, it's different from 집는다(to pick)),밥는(X), the opposite of 의 , it should be after non-final consonant. 가 : 내가/그가/그여자가(O) but 집가(X), 밥가(X) etc. the same as 의 and it's function is to make 'noun' before '가' subject. 내(I)가 왕이다. (I am the king) 를 : 나를/그를/여자를...(O) but 집를(X)/밥를(X)...also should be after non-final consonant. 을 : 밥을(O)/책을(O),..but 을(X)/너을(X) you know that this should be after the final consonant. And both 를 and 을 make the word before it 'object' 나는 책을 샀다. (I bought a book) 나는 집을 샀다(I bought a house) Hope it will help you understand Korean better.