Those are the gentiles who are on earth alive, at His coming when He takes His power unto Himself and is crowned, in heaven, and is after the tribulation is ended.
The sheep gentiles are given the rebirth of spirit [no one who comes to believe in the name of the Son of God will be born of the Spirit in the tribulation, after the Spirit of glory is removed with the raptured believers]. Jesus grants that to those who endure in that time, at His return, and they enter into the restored kingdom of God on earth, which was prepared from the beginning, but which Adam lost, sold into sin and corruption.
The goat gentiles are cast alive, soul in body, into the lake of fire, right then and there.
At that time, also, the "tares/bastard wheat=demons" and those who look human in flesh of the stolen Adam creation, but whose spirits are of the fallen watchers "after the flood" who did the same as those chained ones before the flood did [who were chained as a warning to other watchers to not do the same, as Jude states], are also gathered by the angels and cast alive, minus their stolen flesh bodies, into the lake of fire, for their doom is told of by the prophet Enoch, the seventh from Adam. They do not stand for judgment because God has judged them already, as Enoch revealed in chapter 14/15..
The sheep gentiles and the goat gentiles stand before the "God of the whole earth", who is The Firstborn Son of God, who is God the Word in a garment of human being Kinsman/Redeemer flesh to the Adam creation brother of Him, when, at His return to reign over His ransomed and restored kingdom, the earth is cleansed for the Sabbath rest of it of all things that defile.
The Elect who are gathered are the offspring of Jacob, named "Israel", the New Man name invoked over them as a sign of the adoption of the flesh, to come, and they are gathered by the angels to Mount Sinai, as Enoch the prophet, the seventh from Adam reports, and they are there passed under the "Rod of God", as Ezekiel reports in chapter 20, and the wicked unrepentant Jews/the elect, are cast alive into the lake of fire and the remaining remnant are "the blessed of YHWH", who enter into the restored kingdom of God for the millennial Sabbath, and marry and have children. The sheep Gentiles also are the "blessed of YHWH", who enter into that restored kingdom, and marry and have children, and fill the earth in that blessed time.