What it says is that we will judge the affairs of the angels. We were made a little lower than the angels, but will one day essentially outrank them -though God's government is not as human government.
144,000 is simply the number of servants prepared to minister to people during the "great tribulation" -though their work will not be simple or easy. It will be the most difficult time in human history. Just after they are mentioned, a great multitude is mentioned which will also experience that tribulation, and will be saved out of it to the first resurrection -whether they die in it or life through it until the return of Christ.
Those who have done the daily -prophesied, ministered and preached the gospel of the kingdom before the tribulation will be spared experiencing it -though they will be persecuted fiercely before they go to a place of safety.
They are the woman who goes to the place prepared -and the 144,000 and others are the "remnant of her seed"
Rev 12:14And to the woman were given two wings of a great eagle, that she might fly into the wilderness, into her place, where she is nourished for a time, and times, and half a time, from the face of the serpent.
15And the serpent cast out of his mouth water as a flood after the woman, that he might cause her to be carried away of the flood.
16And the earth helped the woman, and the earth opened her mouth, and swallowed up the flood which the dragon cast out of his mouth.
17And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.