If you’d like to backup your entire profile including passwords, cookies, bookmarks, etc, you can use this method.
Open up the Add-ons screen and find Password Exporter in the list, where you can click the Options button to bring up the Import/Export Passwords dialog.
You can either import or export your passwords using this dialog, and you can choose to encrypt them if you want.
You can export in either XML or CSV format. If you are trying to create a spreadsheet with all your passwords the CSV file would be a better choice.
Just be very careful with the list of passwords you exported.
Download Password Exporter from Mozilla Add-ons