When a regular person files for bankruptcy, they are given exemptions which allow them to keep stuff. For the vast majority of people who file, the exemptions are so large that they get to keep everything that they own. However, a business does not get exemptions.
When a business files for bankruptcy, everything the business owns becomes property of a bankruptcy estate. That estate, and the assets within, is then administered by a Trustee appointed by the Court. That Trustee will do their best to sell any non-cash assets. Then, the Trustee will distribute the remaining cash to the creditors that the business owed money. If any creditors are stilled owed money after that, the debt is discharged (or erased).
Many businesses don’t really have a lot of stuff. Service based businesses, for instance, may not use any tools or produce any products, and instead rely purely on the skills of the owner to generate income. This is especially true for businesses facing bankruptcy, who may have already begun selling off assets in order to pay their bills or who may have stopped operating due to inability to purchase raw materials. However, there are many things that people often don’t think of as business assets, which count as an asset.
When a business with no assets files for bankruptcy, the Trustee is still appointed, but they have nothing to liquidate or distribute, and the creditors walk away with nothing. The debt is still discharged even when there was nothing to distribute to creditors.