To enable Bin Locations for an inventory item in SAP Business One follow these instructions:
1) Inside the Modules tab inside SAP B1 navigate to Inventory > Item Master Data
2) Inside the Item Master Data window navigate to the Inventory Data tab. Double click on the yellow/gold arrow icon next to the warehouse you want to enable bin locations for.
3) Check the checkbox next to Enable Bin Locations. Once you click it, a new tab will appear called Bin Locations. Bin locations are now enabled for the inventory item.