Amazon FBM (Fulfillment by Merchant) is a service model of Amazon and means that the products purchased by customers are stocked, packaged, and distributed by the seller.
If you are a seller on Amazon, it is your responsibility to store, package, and ship your products to customers. You don’t need to leverage Amazon’s warehousing, distribution, and logistics network.
Amazon FBM offers more control and flexibility for sellers but can also include more inventory management, packaging, and distribution tasks.