I tried searching the previous discussion but too many options popped up. I hope this question is new.

When you have to type a word which is described by pictures and you type the article (la/il in italian) it is automatically transfered to the left. However when a word starts with a vowel you need an apostrophe which is automatically transferred to the left.

Sidenote: thank you soo much duolingo for giving me the opportunity to give me some way to keep my italian fresh !