Resurrection, the first
'The first resurrection,' mentioned in Revelation 20:5, 6, does not mean a first resurrection, but the essence and primary part of resurrection, which is salvation and eternal life. There is only one resurrection to life. A second does not happen, and is not mentioned anywhere in the Bible.
(References: Apocalypse Explained 6; Apocalypse Revealed 851; Revelation 20:5-6)
Brimstone
In Revelation 14:10, this signifies the loves of self and the world and pride in intelligence from these loves. (Apocalypse Revealed 636)
In Isaiah 34:9, brimstone signifies filthy lusts.
(References: Arcana Coelestia 643 [1-4])