Setting up swatches for a group used to mean typing each swatch name by hand. If your product titles already contain the color or variant name - like “Classic Shirt - Blue”, “Classic Shirt - Red” - that’s redundant work.
The new Auto-fill swatches button detects the common parts of your product titles and extracts the unique portion as the swatch name. It then matches those names against your existing swatches, so colors and images get assigned automatically.
The button appears in the Products section of the group form when your titles are auto-fillable. It only fills empty fields, so it won’t overwrite anything you’ve already set up manually.