'Serve' in the Bible

As for foreigners who become followers of the Lord and serve him, who love the name of the Lord and want to be his servants -- all who observe the Sabbath and do not defile it, and who are faithful to my covenant --

Foreigners will rebuild your walls; their kings will serve you. Even though I struck you down in my anger, I will restore my favor and have compassion on you.

Indeed, nations or kingdoms that do not serve you will perish; such nations will be totally destroyed.