"나는 그것을 좋아합니다."
Translation:I like that.
No it should not. Read the notes. It says: "Can you say 나 in 합쇼체 (-ㅂ니다)? Definitely yes. 저 is for lowering oneself, and -ㅂ니다 is for raising the listener. If you are higher than the listener, you can raise them by using -ㅂ니다, but you don't have to lower yourself. On the other hand, it is weird to lower yourself and at the same time not raise the listener."
그 means "that", so 그것 means "that (thing)". 이 would be used in place of 그 to be "this" -> 이것 "this (thing)"