"In one year"
Translation:Tra un anno
In Italian, when a word ends with a vowel and the next word begins with a vowel, the sounds would run together. So, bearing that in mind, there is usually a trick that involves putting a consonant in there to prevent this from happening. As my Italian professoressa used to say, "It's to confuse the enemy." It can be frustrating, these exceptions, but with practice and repetition it will become second nature :)
Uno means both "one" and "a", same as the German "ein" or the French "un"; so "in one year" and "in a year" are indistinguishable, and because of the article rules, uno becomes un before vowel.