While you wear this ring, difficult terrain doesn't cost you extra movement. In addition, magic can neither reduce your speed nor cause you to be paralyzed or restrained.
Ring of Free Action in the 2024 rules
The 2024 Dungeon Master’s Guide revised the magic items, and the SRD 5.2 carries the new text. What changed:
Same rarity and attunement; the text is reworded for the 2024 rules glossary.
Type
Ring
Rarity
Rare
Attunement
Required
While you wear this ring, Difficult Terrain doesn't cost you extra movement. In addition, magic can neither reduce any of your Speeds nor cause you to have the Paralyzed or Restrained condition.