These are file types that Windows Phone doesn't play or view—for example, an .ogv video file. If you copied some unrecognized files to your phone from your computer, you can connect your phone to your computer again to delete or move them.
Kung kumopya ka ng ilang hindi nakikilalang file sa telepono mo mula sa computer mo, maaari mong ikonekta muli ang telepono mo sa computer mo para tanggalin o ilipat ang mga ito.