Thus says the LORD, the Redeemer of Israel and his Holy One,
to one deeply despised, abhorred by the nations, the servant of rulers:
“Kings shall see and arise; princes, and they shall prostrate themselves;
because of the LORD, who is faithful, the Holy One of Israel, who has chosen you.”
(Isaiah 49:7)

To understand this prophecy of Isaiah, reading the whole chapter 49 is necessary, but the two proceeding verses (5 & 6) explain clearly what the LORD wants:
1) The Lord wants his people back “that Israel might be gathered to him”
2) God wants the entire earth to know him – “I will give you as a light to the nations,
that my salvation may reach to the end of the earth.” vs.6

An important note about verse 6, it is quite clear that Isaiah is not just a Prophet for Israel, but for us also, for all nations.

With this background, we can then understand the prophetic verse 7, the day will come when everyone, including the rulers of every nation on earth, will prostrate themselves before the LORD.