"The owl has large eyes."
Translation:Le hibou a de grands yeux.
The general rule is that words starting with h with the definite article become l'h. However, there are quite a few words that start with h aspiré (aspirated h), which is pronounced exactly the same but maintains the separate definite article (like le hibou as opposed to l'hibou). Because words starting with h aspiré are pronounced exactly the same as words that take l'h, you just have to memorize them when you come across them. Here's a good list: https://fr.wikipedia.org/wiki/H_aspir%C3%A9
In case you haven't figured it out already: https://www.duolingo.com/comment/944289/What-does-B-A-N-G-S-stand-for