English is very fun, but it's very difficult. ㅜ.ㅜ

english is very fun!!!

but i'm very difficult ㅜ.ㅜ

---> but IT'S very difficult

IT's  [a contraction(It is)just like 이것이 and 이게]

IT= is a pronoun used for something which is not a human<-- XDD ahahah...no seriously (._.  ) "It" is used for things and animals like example

"the book is blue and IT is very old."

Hope this helps :DDD 

english is very fun!!!

but i'm very difficult ㅜ.ㅜ

English is a lot of fun, but it is very difficult!

english is very fun!!!

but its very difficult ㅜ.ㅜ