Breakdown of آنها عصبانی هستند چون تو پنجره را شکستی.
تو
you (singular)
آنها
they
پنجره
window
بودنbudan
to be
Questions & Answers about آنها عصبانی هستند چون تو پنجره را شکستی.
Does using چون (because) change the word order of the sentence that comes after it?
No, it doesn't! The word چون just acts as a bridge between two normal sentences. The second part of the sentence follows the standard Farsi word order: subject (تو), object (پنجره را), and verb at the end (شکستی).
Why is را added right after پنجره (window)?
The word را is a marker that shows us the specific direct object of the verb. Since the people are angry about a specific window being broken (the window, not just any random window), we must use را.
Could I drop the pronouns آنها (they) and تو (you) here?
Yes, you can! In Farsi, the verb endings already tell us who is doing the action. The -ند on هستند means 'they are', and the -ی on شکستی means 'you did it'. Saying عصبانی هستند چون پنجره را شکستی is completely correct and sounds very natural.
I've sometimes seen the word زیرا used for 'because'. Why use چون here?
Both words mean 'because', but چون is much more common in everyday spoken Farsi. زیرا is more formal and is mostly used in writing or polite speech.