We will let Jacob, the brother of Nephi the son of Lehi, and Samuel, the Lamanite, comment on this verse:
O my brethren, hearken unto my word; arouse the faculties of your soul; shake yourselves that ye may awake from the slumber of death; and loose yourselves from the pains of Hell that ye may not become angels to the devil, to be cast into that lake of fire and brimstone which is the second death. (Jacob 3:11)
But behold, the Resurrection of Christ redeemeth mankind, yea, even all mankind, and bringeth them back into the presence of the Lord.
Yea, and it bringeth to pass the condition of repentance, that whosoever repenteth the same is not hewn down and cast into the fire; but whosoever repenteth not is hewn down and cast into the fire; and there cometh upon them again a spiritual death, yea, a second death, for they are cut off again as to things pertaining to righteousness.
Therefore repent ye, repent ye, lest by knowing these things and not doing them ye shall suffer yourselves to come under condemnation, and ye are brought down into this second death. (Samuel the Lamanite, Helaman 14:17-19)