Dimension number or code
The number of digits of your mainbook accounts are defined in your license, you can check all your numbering masks, languages and other stuff in Settings / App and License data tab.
Export group number
Not currently in use.
Dimension name
Enter the name of the dimension here
Foreign dimension name
If you are reporting to an overseas fundraiser or donor, you may add (or receive from them) the dimansion name in their language. This enables them to read your accounting reports in their own language using their own account and dimension naming scheme.