"He eats an apple."
Translation:Han äter ett äpple.
Ett is the indirect article and en the direct article. You use ett with neuter nouns and en with common nouns. For example, ett hus; en bil. When using the direct article, it's huset and bilen. There's no rhyme or reason for which words are ett and which are en. You just simply need to remember which is which.
Your description is confusing since you're mixing up front and end articles.
Let's put it this way instead:
en and ett are both indefinite articles.
en is used for common gender nouns: en bok 'a book'
ett is used for neuter nouns ett äpple 'an apple'.
The definite form is created by using endings:
en bok 'a book' -> boken 'the book'
ett äpple 'an apple' -> äpplet 'the apple'
You can also download a Swedish keyboard. I have Win 8.1 and it was simple. Probably works in Win 7, but I'm not sure as I skipped 7. Go to Control Panel/Clock, Language, Region/Add a language. Easy peasy from there. Click on the one you want and install. And then to toggle between keyboards, you can either left click on the "ENG" on the taskbar, or click and hold the Windows key and then click the space bar. If you hold the Windows key while clicking on the space bar, you can toggle between all installed keyboards should you have more than one.
http://sv.forvo.com/search/h%C3%A4n%20%C3%A4ter%20ett%20%C3%A4pple/sv/ pronounces hän "heen" and Han "hun" what does each mean? and äter is more of "aiter"
All Swedish nouns have a grammatical gender. In the case of äpple, it's of the neuter ett gender. For some more info, please have a look here: https://forum.duolingo.com/comment/26420394/Answers-to-some-common-questions-on-grammar-that-beginners-have
Swedish doesn't have masculine / feminine. Our nouns have genders called "common" and "neuter". Please have a look here: https://forum.duolingo.com/comment/26420394/Answers-to-some-common-questions-on-grammar-that-beginners-have
You're supposed to be allowed one typo per word, as long as it doesn't turn into another word. And you're also supposed to be shown that "we let you through, but you had a typo here".
Unfortunately, the former system doesn't work well for Swedish, and the latter is buggy.