Enchant
Enchant is a keyword ability that restricts what an Aura can target and be attached to. Aura is an enchantment type.
From the Comprehensive Rules (November 8, 2024—Edge of Eternities)
- 702.5. Enchant
- 702.5a Enchant is a static ability, written “Enchant [object or player].” The enchant ability restricts what an Aura spell can target and what an Aura can enchant.
- 702.5b For more information about Auras, see rule 303, “Enchantments.”
- 702.5c If an Aura has multiple instances of enchant, all of them apply. The Aura’s target must follow the restrictions from all the instances of enchant. The Aura can enchant only objects or players that match all of its enchant abilities.
- 702.5d Auras that can enchant a player can target and be attached to players. Such Auras can’t target permanents and can’t be attached to permanents.

Enchant in practice
Enchant a creature, player or land, these are forms of powering up pieces in play or controlling them as is the case for Aura Curses that enchant players and apply a devastating effect on them.
There is a particular case when these types of enchantments return to the battlefield as the reanimate ability is what goes on the stack and not the enchant per se Enchant Creature could target a Hexproof or Shroud creature, but remember this only applies when bringing back the enchantments from graveyard to play.

