FreeBSD uses its own hard disk partition scheme on your PC. It
requires only one entry in the primary partition table of your disk
and manages it similarly to DOS extended partitions, putting in its
first sector a new partition table in BSD disklabel format. Saying Y
here allows you to read these disklabels and further mount FreeBSD
partitions from within Linux if you have also said Y to "UFS
file system support", above. If you don't know what all this is
about, say N.