I Need Clarification Of A Specific Part Of Placed_Features 1.20.1

{
  "feature": "minecraft:ore_copper_small",
  "placement": [
    {
      "type": "minecraft:count",
      "count": 20
    },
    {
      "type": "minecraft:in_square"
    },
    {
      "type": "minecraft:height_range",
      "height": {
        "type": "minecraft:trapezoid",
        "max_inclusive": {
          "absolute": 112
        },
        "min_inclusive": {
          "absolute": -16
        }
      }
    },
    {
      "type": "minecraft:biome"
    }
  ]
}```

What is this section?
```json
{
  "type": "minecraft:biome"
}

And what value is it specifically checking?