Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power,...And death and hell [the grave] were cast into the lake of fire. This is the second death.
Revelation 20:6,11
*1st Death: You can come back from that one- for example Lazarus was raised once, and at the 2nd Advent likely raised again.
*2nd Death: You won't be coming back....