en_tn_condensed/act/13/47.md

commanded us ... 'I have appointed you as a light ... you should bring salvation to the uttermost parts of the earth.'

Both instances of "you" here are singular, but when Paul said, "... the Lord commanded us," Paul was applying those singular words to both himself and Barnabas. The words in the quotation were originally spoken by God through Isaiah the prophet to God's servant. By quoting Isaiah's prophecy, Paul was saying that he and Barnabas were doing what God commanded his servant to do. Paul was not saying that God had spoken directly to him.

as a light

Here the truth about Jesus that Paul was preaching is spoken of as if it were a light that allowed people to see.

bring salvation to the uttermost parts of the earth

"tell people everywhere in the world that I want to save them"