Learn French: Il est dix heures, l'exposition commence. - It is ten o'clock, the exhibition is starting.

When telling the time in French, you always use il est. Even though c'est is often used for "it is" in other everyday situations, reading the clock is a strict exception where only il est is correct.

Does heures mean "o'clock" or "hours"?

It actually means "hours," but French uses it exactly where English uses "o'clock." Instead of saying "ten o'clock," French speakers literally say "it is ten hours."

Why is it l'exposition instead of la exposition?

Exposition is a feminine noun, but because it starts with a vowel, the a in la is dropped and replaced with an apostrophe. This makes the words flow together smoothly without a pause in the middle.

Why does commence translate to "is starting" rather than just "starts"?

French only has one present tense. The single word commence covers both "starts" (a general fact) and "is starting" (happening right now). The English translation just picks the one that sounds most natural for this specific situation.