The words “Repent” and “turn” refer to changing one’s way of thinking, turning away from sin and turning to God. It is a way of saying the same thing for emphasis. (See: rc://en/ta/man/translate/figs-parallelism)
“Blotted out” here is a metaphor, as if our sins were recorded with ink, but when God forgives our sins, they are removed, or erased. This can be stated in active form. AT: “so that God may remove your sins” (See: rc://en/ta/man/translate/figs-activepassive) (See: rc://en/ta/man/translate/figs-metaphor).
“times of relief from the presence of the Lord.” Possible meanings are 1) “times when God will strengthen your spirits” or 2) “times when God will revive you”
Here the words “presence of the Lord” is a metonym for the Lord himself. AT: “from the Lord” (See: rc://en/ta/man/translate/figs-metonymy)
“that he may again send the Christ.” This refers to Christ’s coming again.
This may be stated in active form. AT: “whom he has appointed for you” (See: rc://en/ta/man/translate/figs-activepassive)