For every field you create, we create a "Snippet" liquid template. If you need some code to get your theme customization started, or just need the namespace and key for a particular field, there are two ways to get it.
Assuming you're looking for information about a field attached to a product, go to Products -> Install -> Manual Install -> Advanced.
Within the app, we provide a theme snippet editor for each field. Within the editor, we also provide this information. Click on +Configure Fields > Edit
The Snippet Editor is a really helpful tool to edit and change what a field has and prints. A fields key is based on what you set as the Machine Name in custom fields. You can edit a machine name before you finish creating a new field by clicking the edit link next to the Machine name form.
Custom Fields is a Shopify metafield creator and editor. Metafields are made up of a namespace, a key, and a value. The namespace and key can be seen in the Shopify print statements, while the value can be directly added in Custom Fields on a per-product/page/etc. basis.
Typically, Shopify metafield values can either be strings or integers, however Custom Fields has a number of different types of metafields. Read more about types of metafields here: https://support.apps.bonify.io/hc/en-us/sections/360001179812-Types-of-Fields-How-to-Manage-Them