Now

This word is used here to mark a break in the main story line. Here Matthew starts to tell a new part of the story.

from the sixth hour ... until the ninth hour

"from about noon ... for three hours" or "from about twelve o'clock midday ... until about three o'clock in the afternoon"

The word "darkness" is an abstract noun. AT: "it became dark over the whole land" (See: rc://en/ta/man/translate/figs-abstractnouns)

"Jesus called out" or "Jesus shouted"

These words are what Jesus cried out in his own language. Translators usually leave these words as is. (See: rc://en/ta/man/translate/translate-transliterate)