The field path is the hierarchy of the field, the path you use to find it. To configure filters or display patterns, you must access the value via field ID or field path. The field path always starts with lowercase letters. 

layerId.fieldId

Go to Schemas > Indexing. There, you find the field path of every field of the schema. To copy it, click on the value.

• Visual representation of the hierarchy of the field path syntax
  • productInformation.products
  • descriptiveKeyword.keywords
  • multimediaInformation.sources