"I want an orange, I eat an orange."
Translation:Saya mau jeruk, saya makan jeruk.
There are some other ways to say this in Indonesian, those are "Saya mau sebuah jeruk, saya makan sebuah jeruk.", "Saya ingin jeruk, saya makan jeruk.", "Saya ingin sebuah jeruk, saya makan sebuah jeruk.", and if you want to make the sentence slightly less formal, you can change the word "saya" which means "I, me, my" to be "aku" which also means the same as "saya".
I just wrote it in Bahasa, but I wrote aku and saya in the same sentence and it's wrong. Is there a real rule to use the same word in a single sentence? "Aku mau jeruk, saya makan jeruk"
It's because you have to be consistent with the pronoun you're using. Here, people only use one form to talk to the same person in the same sentence. If you already used aku, then keep using aku for the next.