"Why do you rush?"
Translation:Waarom haasten jullie je?
It's a reflexive verb, meaning it takes the same subject as object. When translated as "Waarom haast je je?" (with singular "you"), you can think of the first "je" as being the unstressed "jij" (subject), and the second being the unstressed "jezelf" (reflexive object).
In English, we would say "Why do you rush yourself?"; the difference is that "yourself" is optional in English, but not in Dutch.
Another way to think about it is to rephrase the sentence so that it's not a question. Then there is a clear separation between the subject "je" and the object "je":
Je haast je omdat je geen geduld hebt (You rush yourself because you have no patience)
Because the "t" is part of the verb's root, so it never goes away: "haasten"
- Ik haast me
- Jij haast je
- Hij haast zich
- Wij haasten ons