If you'd like to export your current database snapshot, please go to MoneyWiz Settings > Database & Export > Export database. On iOS, you'll be asked to select where to "export" the file: you can send it via e-mail, upload it to cloud using iCloud, Dropbox, etc. You can also save it to Apple Files.app. On Mac, you'll be asked where to save the file. The database is in form of a ZIP file.
If you already have a backup made earlier and wish to restore using it, please go to MoneyWiz Settings > Database & Export > Replace database, select file. You'll be asked to point to the ZIP file. Please note that if you're using MoneyWiz Cloud, the restore involves more steps so before proceeding, please see this guide.