2024 Phb Species Meaning. However, unlike with subraces in previous books, legacies aren't listed in the 2024 phb's content preview's as part of the what's in there. This one is easier to answer:

The new phb is being released as part of the larger one d&d update, the code name for wizards of the coast’s ongoing playtest and retooling of the d&d fifth edition. The 2024 phb also brings in the extra subclass options introduced in xanathar’s guide to everything, meaning this new phb has a majority of the player.