FBA=Fulfillment by Amazon. That means Amazon allows sellers to send their inventory to Amazon’s fulfillment centers where Amazon will handle picking, packing, shipping, customer service and returns. FBA products are eligible for Prime free 2-day shipping as well as free shipping on eligible orders.
According to Amazon, the company now operates more than 75 fulfillment centers and 25 sortation centers across North America and each of them gets their own warehouse code; the code format is 3 letters with 1 number such as ONT8, FTW1, etc.