A document is generated from a template and a data item by replacing the merge tags with the actual data.
Single Document Generation: Whenever you initiate a document generation with one data item, a single document is created. Consequently, your monthly usage is increased by one.
Batch Document Generation: If your document generation is based on multiple data items, each one accounts for a unique document generation. In this case, your monthly usage will be increased by the number of data items used.