From publisher blurb:
Under rare circumstances, a powerful soul suffused with arcane magic will persist beyond a single life. As a sorcerer masters their magical abilities, they may find these experiences familiar when they begin to remember fragments of their past lives. These past lives are seldom identical in personality, though, and a Reincarnate sorcerer may even find themself capable of consulting the spirits of these past lives for guidance and unique perspectives of the world lost to shorter-lived souls.
Building off of the existing Fifth Edition rules to build a sorcerer character, the Reincarnate Soul allows a player to build a sorcerer whose power comes from a cycle of reincarnation, allowing them to remember powers from past lifetimes. This PDF also contains a new metamagic option for all sorcerers to cast more persistent spells.