Bright is an effect that is applied to food and elixirs in Tears of the Kingdom.
Tears of the Kingdom
"Grants a [x]-level glow effect, illuminating your immediate surroundings. This faint luminescence is a boon in dark places."
Bright meals are created when Link cooks Brightcaps or Glowing Cave Fish in a Cooking Pot as part of a meal (with no conflicting effects); similarly, a Bright Elixir can be made by cooking Deep Fireflies with Monster Parts. This effect is primarily useful in the Depths in the areas untouched by a Lightroot, and in caves with no immediate light.
Bright meals & elixirs give Link the Glow effect, causing him to light up an area around him. The Miner's Set provides a permanent Level 1 Glow around Link with each of its three pieces, and all together produce a permenant Level 3 Glow, lighting up a wide area around Link. When upgraded at least twice, Link gains the bonus effect of Shining Steps, allowing Link to leave a path behind him that continues to illuminate for a period of time.