Learn Russian: Спасибо за правду. Тебе хватило смелости всё сказать. - Thanks for the truth. You had the courage to say everything.

This is an impersonal construction. There is no nominative subject here. The person experiencing the sufficiency is in the dative case (тебе) and the thing they have enough of is in the genitive case (смелости). Without a grammatical subject, the past tense verb defaults to the neuter singular form (хватило).

Why is it смелости instead of смелость?

The verb хватить (to be enough / to suffice) requires the thing you have enough of to be in the genitive case. Смелость (courage) is a feminine noun ending in a soft sign, so its genitive form ends in -и.

Why are both verbs (хватило, сказать) perfective here?

The speaker is focusing on a single, successful result. The person successfully mustered enough courage on this specific occasion (хватило, the perfective of хватать), and the action they completed was stating the whole truth (сказать, the perfective of говорить).

Is there a reason всё comes before сказать instead of after?