Enchantments are special implicit modifiers that can be applied to items upon completing the lab. Enchants can grant the player special skills, temporary buffs or changes to specific skills.
Completing the harder Labyrinths allows the player to enchant different items, the higher tiered the Labyrinth is, the better the enchantment will be. . The Normal Labyrinth allows glove enchantments. The Cruel Labyrinth allows glove and boots enchantments. The Merciless and The Eternal Labyrinth offer all three glove, boot and helmet enchantments.
For extra information feel free to check the wiki page.
Below is a list of all the enchantments you can get from the various Labs