It's idiomatic / I don't think there's much to understand literally here. Literally the structure is "it makes / it does <amount of time>". The closest in English might be something like "today makes 10 years since I moved to this city", but I think that sounds awkward.
Because words can have several meanings. The first English example I can think of is the word 'mean'. In your everyday conversation you will know based on context what the word is supposed to mean. In the duolingo exercises it is your job to look at the sentence and find the meaning of the word that makes sense with the rest of the sentence (sometimes several will work).
Hi Matzebra13 Sometimes just remembering that is the right answer is the best way with languages. If you can remember then you're not so thick as you say. http://www.spanishdict.com/translate/Hace this link could help Hacer has a lot of different meanings depending on sentence structure. If you make not of the green headings on the link that should really give you the answers you need. The word Atrás can also be used for ago. Tho I am under the impression one precedes the sentence and the other follows. Hope this helps. I have to kp checking it but if you can remember then seriously no thick head. Good luck
I tested out of some skills, but i always practice them later on and I don't recall using hace to mean ago, but maybe it just didn't come up.
For ambiguous statements like this, duolingo should give us some context. I interpreted the sentence to mean "it makes 15 years", as in "today makes 15 years since I buried my goldfish"
this strikes me as ambiguous or like a response to a question...
Q: How long has she been incarcerated? A: Hace quince años. Q: How long have you been sober? A: Hace quince años. I have not seen you for a long time. ¡Hace quince años!
I am not a native Spanish speaker but is this correct? does my thinking here make any sense?