This configuration option is used for mapping Additional Expense Names in SAP Business One to SPS Allowance and Charges Qualifiers.
Additional Expense Names are configured by navigating to Administration > Setup > General > Freight. Note that an Allowance will be setup as a negative charge in SAP Business One.
The Integration Configuration screen can be opened in SAP Business One: SPS Integration > SPS Integration Setup > Integration Configuration. See the screenshot below for an example of mapping Additional Expenses.
Refer to the SPS Qualifiers List of Allowance and Charge Codes for a full list of valid mappings.