In PrestaShop attributes are the basis of product variations. Each product can have some specification like color, size, material etc. Each attribute group can have some attribute values:
color: red, blue, green, white
material: wood, plastic, metal, paper
The difference between an attribute and a feature depends on the product itself. Some products might share the same property, one being an attribute built for building product variations, another one being simply an invariable feature.
For instance, a customer can buy an iPod variation based on attributes (color, disk space) but not on features (weight, size).
Likewise, another shop might sell t-shirts variations based on attributes (color, size, gender) but not on features (weight).
How to get product attribute group ID?
To get an ID of attribute group (in this example ID of group color / size / material) you have to login to your shop back office, theb please go to Catalog > product attributes. You can find there a list of all available attribute groups in your shop. The ID is available inside first column, exactly as image below shows: