This is part of a long Messianic prophecy (all texts from The NWT):-
Isaiah 59:20 “To Zion the Repurchaser will come,. . ."
Isaiah 60:5 "At that time you will see and become radiant, And your heart will throb and overflow, Because the wealth of the sea will be directed to you; The resources of the nations will come to you."
As vs. 5 is in the midst of a Messianic prophecy it is referring to people coming to Jesus from the nations of the earth and using all their power, goods, lives etc. is service to God as Christians.
Isaiah 61:1 "The spirit of the Sovereign Lord Jehovah is upon me [Jesus], Because Jehovah anointed [Messiah] me to declare good news to the meek. He sent me to bind up the brokenhearted, To proclaim liberty to the captives And the wide opening of the eyes to the prisoners,
X-ref to the above:-
Luke 4:17-21 "So the scroll of the prophet Isaiah was handed to him [Jesus], and he opened the scroll and found the place where it was written: 18 “Jehovah’s spirit is upon me, because he anointed me to declare good news to the poor. He sent me to proclaim liberty to the captives and a recovery of sight to the blind, to send the crushed ones away free, 19 to preach Jehovah’s acceptable year.” 20 With that he rolled up the scroll, handed it back to the attendant, and sat down; and the eyes of all in the synagogue were intently fixed on him. 21 Then he began to say to them: “Today this scripture that you just heard is fulfilled.”
Isaiah 62:11 "Look! Jehovah has proclaimed to the ends of the earth: “Say to the daughter of Zion, ‘Look! Your salvation is coming. Look! His reward is with HIM, And the wage he pays is before him.’”
Galations 3:14 "This was so that the blessing of Abraham would come to the nations by means of Christ Jesus,. . ."
Below is From http://www.jesuswalk.com/isaiah/11_glory.htm:-
Then you will look and be radiant,
your heart will throb and swell with joy;
the wealth on the seas will be brought to you,
to you the riches of the nations will come." (60:4-5)
"Jerusalem" is a kind of shorthand to refer to the people of God ... Thus some of this prophecy is being fulfilled by the spread of the Christian church throughout history.