Product identification is used to import product identifiers. Product identifiers are used to identify a product and generally used to store barcodes for products. You can have multiple types of identifiers for different types of barcodes (UPC, EAN etc).
The import can be found from the Tools Menu Item, Getting Started, Product Identification.
Download the template to see what fields you need to provide.
In the template file, you will specify the part number of the product, the unit used for the product. identification_type_name is for the type of barcode it is. This is free form text so put anything you want here. Use EAN or UPC for example.
The value column is the actual value of the barcode.
Once the product identifiers are loaded, you can see them when viewing the product page.