If you go to "Setup > Edit Mapping", you will get a screen that's similar to the one below. On the left side, you have the "Import fields", which are the fields that Channable found in your import feed or import webshop connection. On the right side you have the "Internal Channable fields", where you can set the name for the Import fields as soon as they enter Channable.
By checking the "Custom" tickmark on the right side, you can freely name your field anything. However, if you uncheck the "Custom" tickmark, you will get a dropdown menu with the standard field names Channable uses. The advantage of using a standard Channable field name is that our system will automatically show the right information in the Products menu item, and more importantly, it will automatically connect most of your fields in the Finalize/Build step of creating a Channel or API. So basically, using standard Channable field names gives you a better overview of your data in the product overview and saves you precious time when setting up export Channels or APIs.
Add a new field
In some cases you might need to add information that's not present in your import feed yet, for example to set the age_group of your products (adults, kids etc). To do that you'll need to add a new field. You can add a new field by scrolling to the bottom of the mapping and click on '+ add new field'. It is recommended that you use a standard Channable field name, this makes it easier to set up Channels later on. Click on 'Custom' and select a field from the drop down bar. If you can not find a field name that matches your desire you can click on custom again and choose a name.