Product Weight

Each product can have the weight defined. The weight field appears inside the product details box on product add/edit screen:

Product Details Box SKU

Set Catalog Weight Unit

In order to change the weight unit go to the Catalog Settings > Attributes. The weight unit option is available below the attributes table:

Size Weight Settings

You can also disable the weight feature completely. In order to achieve it go to the Catalog Settings > Attributes and switch the Weight Unit option to Disable Weight.

Disable Size Weight Settings