Translation:A woman reads.
Being a native korean ( 11 years old but still fluent ) myself, I'd like to point out something that could help.
Duolingo's Korean course is the very formal way of talking. When saying the "니다" part, that's the way of talking to elders in a formal way of language. If talking to peers or people younger than you, I don't recommend using that kind of ending to your sentences.
Hope this helped, have a great day :)
니다 is how we show that something is happening or is true or does exist. It makes the different between putting together a broken list of words like "me swim" and saying "I am swimming". That's my understanding at least. I have seen better explanations in other comments.
It depends on the instructions that you were given. Some people are told to write what they hear, but they translate instead and are marked wrong. Then, Duolingo shows the translation in case you wanted to know, but the answer was the original sentence for that exercise.