In almost all screens of SAP GUI you can export information to Excel.
The only problem sometimes is that the export button is not at the same place.
Remember that the file you export is saved in your MACHINE.
In some transactions you will find it here:
or here:
But in MOST cases go directly here:
For users that have the appropriate authorizations, have the capability to export the Sales Invoices to PDF files in their disk.
Transaction: ZHGISD_LEGDOC_TO_PDF
The manual of operations:
HGI-IBM_SAP_SD_Mass_Export_to_PDF.docx