Learn Italian: L'imperatore creò la legge e il senato la confermò. - The emperor created the law and the senate confirmed it.

They are conjugated in the passato remoto (historic past). For regular -are verbs like creare and confermare, the third-person singular (he/she/it) form always ends in an accented -ò. The accent is very important because without it, creo means "I create" and confermo means "I confirm" in the present tense!

When should I use this historic past tense instead of the regular passato prossimo (like ha creato)?

The passato remoto is used for events that happened in the distant past and are completely finished, with no emotional or timeline connection to the present. You will mostly encounter it in literature, historical texts, and storytelling. That is why it pairs perfectly with words like imperatore (emperor) and senato (senate).

What is the word la doing right before confermò?

It is a direct object pronoun meaning "it". It replaces la legge (the law) so we do not have to repeat the word. Remember that in Italian, these object pronouns are placed directly before the conjugated verb, so it literally reads "the senate it confirmed".

Why aren't imperatore and senato capitalized in Italian?

Italian uses capital letters much less frequently than English. Titles of rulers and names of governmental institutions are usually written in lowercase unless they start a sentence or form part of a specific official proper name.