What is a scopable attribute?
For a same product, some of your attributes can different values depending on the channel. For instance, you can have a different descriptions for your e-commerce website and your mobile application or different pictures!
Instead of multiplying the number of attributes (description_ecommerce, description_mobile, …) you can create in Akeneo a scopable attribute, to do so, create one attribute and set its scope to ‘Channel’ (‘Global’ means that the value will be the same for all channels).
An attribute with a ‘channel’ scope will allow the user to fill a different value for each activated channel directly from the product edit form.