After install pkg install virtualbox-ose and following the Handbook (https://www.freebsd.org/doc/handbook/virtualization-host-virtualbox.html) everything was okay but after reboot when I try to run:
[root@freeBSD ~]# virtualbox
Qt WARNING: could not connect to display
Qt FATAL: This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: bsdfb, minimal, offscreen, vnc, xcb.
Abort trap (core dumped)
Do you have X started?