"A man and a boy"
Translation:Een man en een jongen
Wrong, the vowel in 'een' is pronounced like a schwa [ə], so the pronunciation is [ən]. The spelling here is kinda misleading because 'ee' usually represents the [eː] sound.
In Dutch, while distinguishing 'one' from 'a', we add diacritics, so one becomes 'één', which is pronounced regularly like [eːn].
'En' is indeed pronounced like the letter 'N' [ɛn].
That suggests you have a large font (or a small screen). Shrink the font to a size where you can see something that's definitely below the word bank. Depending on your system, you may also be able to move the text up and down. Also, this is the way to switch off the word bank as well, thus you should be able to do things yourself.
"Explain your answer?" Well, for every language accepted as original, there should be a 0th lesson that teaches you how Duolingo works. That way, you wouldn't accidentally try to enter the right answer if the exercise is really multiple-choice. That's about all I can think of.