Learn Italian: L'oracolo disse la verità al mortale. - The oracle told the truth to the mortal.

Disse is the passato remoto (historical past) of dire (to say/tell) for lui/lei (he/she/it). Dire is highly irregular in this tense. Instead of using a standard ending, the root changes to diss- for the first person singular (io dissi), third person singular (lui/lei disse), and third person plural (loro dissero).

Why do we use disse here instead of parlò?

Dire (which gives us disse) means "to say" or "to tell," which takes a direct object—in this case, what is being told is la verità (the truth). Parlare (which would become parlò) means "to speak" or "to talk" and doesn't take a direct object in this way.

Why does verità have an accent on the last letter?

The accent marks that the spoken stress falls on the final syllable. As a quick refresher, feminine nouns ending in -tà are invariable. This means they don't change their ending in the plural. If the oracle told multiple truths, it would be le verità.

Mortale looks like an adjective. Can it be used as a noun like it is here?