en_tn_lite_do_not_use/act/03/21.md

until the time of the restoration of all things

Possible meanings are 1) "until the time when God will restore all things" or 2) "until the time when God will fulfill everything that he foretold."

about which God spoke from ancient times by the mouth of his holy prophets

"about which things God spoke long ago by telling his holy prophets to speak about them"

the mouth of his holy prophets

"the words of his holy prophets"