"The child throws the ball."
Translation:아이가 공을 던집니다.
I believe 가 means "the", while 눈 means "a". Plus, the word 아이 is child, so don't separate 이 from 아.
I don't understand well the particles 이/가 and 은/는, but I am pretty sure it has nothing to do with the articles "the" and "a/an" in English. You are right about not separating 아 and 이 in this case, as together they form the word child (아이).
Korean does not have articles, nor are there any structures in Korean that directly analogue English "a/an" or "the"; these are understood only through context in Korean. 는/은 is the topic marker and 가/이 is the subject marker; English doesn't have a direct analogue for these particles, as subject is marked only by word order (i.e. it always comes before the verb) and topic is understood only through context.
What's wrong with 아이가 instead of 아이는? It's'the child' here.not 'a child' .i am getting some confusion streaks!!!!!!
Korean doesn't distinguish between definite (the) and indefinite (a/an) like English does; -는 marks the conversation topic and -가/이 marks the sentence subject. Korean grammar is extremely different from what you see in Western European languages, but if you keep practicing you'll get a feel for it.