When you import a VM you are adding it to your VM Library. Hopefully when the VM was exported hopefully all removeable media was unmounted, the hardware version is compatible with your type-2 hypervisor and the file(s) provided are not corrupt. 

The process is similar across VMware type-2 hypervisors. I have provided a demo of importing a VM to VMware Fusion. 

The process is almost the same in VirtualBox, except the menu item you'll want to select is called "Import Appliance...".