A line item is a service and each line item is configured from several pieces of data such as its title, description and price. It's important that you know how to configure every aspect of a line item because there are some really cool features in there.
Line Item Label
This is the title of the service which will be displayed to your clients in the proposal tool and into the proposal that gets produced.
If you have connected your GoProposal app up to something like Xero, QuickBooks or Karbon, then you may have an integration section of the Line Item. This is where you could attribute this specific line item to a an Account Code in Xero or a Workflow in Karbon for example.