If you have an existing virtual machine in Open Virtualization Format (OVF or OVA), you can easily import the virtual machine into VirtualBox. If you use VirtualBox on Mac, start VirtualBox, then go to the File menu, choose Import Appliance from the drop-down menu. VirtualBox refers to virtual machines as appliances. The Appliance to import dialog pops up where you can choose the source to import appliance from.
Select the virtual machine file in .ova format to import. Wait a few seconds for VirtualBox to read the information on the file.
Alternatively, you can also click Import from the top menu bar of the Oracle VM VirtualBox Manager to quickly open the above Appliance to import dialog.
VirtualBox will read the information on the virtual machine file, display its properties in the next Appliance settings window. Here you can also change some of the properties or settings by double-clicking on the item or using the check boxes to enable or disable some options.
In fact, except above mentioned methods, you can directly double click the .ova file in Finder, the VirtualBox application will launch automatically and present you the Appliance settings screen as shown above where you can tweak the settings before importing the virtual machine.
When you are ready, click Import button to start the virtual machine importing process which may take a while. It took me about 15 to 20 minutes to import a Windows 11 virtual machine to Mac via VirtualBox. After the process completes, you will find the new virtual machine on the left panel of Oracle VM VirtualBox Manager.