The LORD shall count, when he writeth up the people, that this man was born there. Selah. The Lord shall count, when he writeth up the people - בכתוב עמים bichthob ammim, in the register of the people. When he takes account of those who dwell in Jerusalem, he will particularly note those who were born in Zion.
This has an easy spiritual meaning. When God takes an account of all professing Christians, he will set apart those for inhabitants of the New Jerusalem who were born in Zion, who were born again, received a new nature, and were fitted for heaven.