"Tú cierras la ventana."
Translation:You are closing the window.
It could be either. The two similar-looking tenses in the two languages do not match up directly.
Absolutely not. And I'm a bit disappointed, as I was expecting a request/command sentence be given to me to translate. This is my first sentence in the exercise though, so still crossing my fingers :).
You is implied in English. If you're requesting/demanding someone do something, it's "Close the window." That should be the answer DL gives.
No. You can make a command in Spanish as you can in English. This was not such an example so it should NOT be 'Close the window!'.
(Cierra la ventana!)
The present progressive would be estás cerrando la ventana. They're different.
But in Spanish you can use the simple present to describe things happening now. See here: https://www.spanishdict.com/guide/spanish-present-progressive-forms
"You close the window" and "you are closing the window" are equally correct answers. Unfortunately, Spanish Duolingo tends to confuse people by making too extreme a distinction in meaning between Spanish present tense and present progressive.