Learn Italian: Questo genio ha creato un'opera importante quando era giovane. - This genius created an important work when he was young.

This highlights the main difference between the two past tenses. We use the passato prossimo, ha creato, because creating the work was a single, completed action in the past. We use the imperfetto, era, because being young is a description of an ongoing state or background information over a period of time, rather than a sudden event.

Why is there an apostrophe in un'opera?

Opera is a feminine noun that starts with a vowel. When the feminine indefinite article una comes before a vowel, it drops its final -a and takes an apostrophe to make pronunciation smoother. Remember that masculine words starting with a vowel just use un without an apostrophe!

The noun opera is feminine, so why does the adjective importante end in -e instead of -a?

In Italian, adjectives that end in -e in their base form (like importante and giovane) do not change for gender. They stay exactly the same whether they describe a masculine or a feminine noun. They only change their ending to -i when they become plural.

Does opera mean a musical opera here?