Translation:Are you crying? I do not want you to cry.
Note, that the English sentence uses a non-finite clause instead of a subclause ("I do not want that you cry"). The corresponding non-finite clause in Finnish would be "En halua sinun itkevän", but that sounds a little bit literary and in contemporary speech most would opt for the given subclause.
I'm hoping one day that there will be a Tips section explaining when that että is used, and how to recognize when to apply it. I can intuit how it works, and translate it just fine, but I thus far haven't been able to foresee when it will or should be used. I'm confident that left to my own devices I would have incorrectly tried to translate "I do not want you to cry" as en halua sinä (or maybe sinua) itkea.
If you speak English as your mother tongue, you are clearly hampered by it in this case. However if you speak some other germanic language this should be clearer.
- Jag vill inte att du gråter.
- Ich will nicht daß du weinst.
I don't know about other languages but given that Esperanto uses a similar construction
- Mi ne volas, ke vi ploras.
I assume that the Romance languages also use a that-subclause, että-sivulause.
What could help English-speakers to see that there is a subclause, are the finite(*) verbs, here en halua and itket. The persons are different (I resp. you), so they cannot be in the same clause according to the Finnish grammar. Actually since there is no coordinating conjunction (e.g. ja : and), one of the clauses must be a main clause and the other a subclause (hence a comma in the sentence). While there are several types of subclauses, a that-subclause is one of the most common ones.
*: See my other comment with the remark of non-finite clause. ADVANCED CONTENT WARNING! In English a verb has three non-finite forms, one infinitive ("to cry") and two participles (present "crying" and past "cried"). In Finnish there are five infinitives and six participles and they declinate in many grammatical cases giving mindblowing words which require multiple words in English to express the same message.
Okay, that's a good tip: when there are two verbs, both finite, but referring to different people, there needs to be a conjunction. If there isn't a coordinating conjunction such as ja, there's a good chance it's a good place to use an että.
Yeah, I'm not even going to look at anything tagged "Advanced Content." My head already hurts trying to get a grasp on the basics.