A warehouse is an additional feature, activated per request to store products in different locations.
Once activated, it can be access from Accounts>>Warehouse tab.
Click the plus icon to add the warehouses.
In new User Interface by clicking the Action button, you can edit/delete warehouse and see products in it.
To add a product to the warehouse, go to Accounts >> Accounting >> Products/Services. Choose the product and open it.
After that find the Inventory Stock Information and select the warehouse.