Questions & Answers about Treinamento começa às oito.
às is the contraction of the preposition a + the feminine plural article as.
It really means “at the hours,” since horas is implied.
à) marks the contraction between a (preposition) and as (article) and distinguishes it from the standalone article as.In Portuguese, c before a, o or u is normally /k/. To show the /s/ sound before these vowels, we use ç.
So começar → começa keeps the /s/ sound in the third-person singular.