"That child wants to drink water."
Translation:Đứa trẻ kia muốn uống nước.
In the phrase "dua tre kia" the word "kia" has a role of a pronoun which means "that". But if you change its position then it becomes a different part of speech. If you say "kia la dua tre" then it means "there is a child". The words in Vietnamese have a fixed order, if you change the order then words can get a different meaning by changing its role in the sentence.