This article describes what an OVA file is: there are two primary formats that use this extension. We'll look at how to open both types, and how to convert your file to another format.
How to Import OVA Files into VirtualBox
A file with the .OVA file extension is most likely a virtual device file used by virtualization programs to store various files associated with a virtual machine (VM).
The file is saved in the Open Virtualization Format (OVF) as a TAR archive. Some of the files you might find inside it are disk images (such as VMDKs), an OVF descriptor XML-based text file, ISOs or other resource files, certificate files, and an MF manifest file.
Because the OVF format is a standard, it can be used by a virtual machine program to export the VM data files so that they can be imported into another application. For example, VirtualBox can export one of its VMs to an archive package with the file extension .OVA that contains an OVF and VMDK file.