This refers to Jesus, the one through whom God would save people. (See: [[rc://en/ta/man/translate/figs-metonymy]])
## have prepared ##
"have planned" or "caused to happen"
## in the sight of all peoples ##
"for all people groups to see"
## He will be ##
This refers to the one who will provide salvation.
## light for revealing truth ##
This could be translated as "this child will enable people to perceive accurately the truth of God, as light allows people to see accurately." (See: [[rc://en/ta/man/translate/figs-metaphor]])
## will be the glory of your people Israel ##
This could be translated as "he will be the reason that glory will come to your people Israel."