This action menu item creates a new company location using the information that would be in common with the currently open company location record.
When you click this button a new company location window will open and will fill out the company name (company name is how locations are grouped together), the drop down list items, default terms, user fields and the website.
Obviously, if you are entering a new location for an existing company, you would not be using the same location name or address, so those items are stripped out of the new location.
Although this function can be useful, it is much easier (and recommended) that you enter new company location records by using the Prospecting Tool.
Also, be careful when entering new Vendor locations in this manner that you change the company type to something other than "Vendor". There should only be one location that is set to Vendor to avoid confusion when entering new parts for sale from the vendor. Entering more than one vendor with the same company name would give more than one choice of vendor when adding parts or creating MFG Codes. It would also create multiple purchase orders where there should only be one.