From LQWiki

lvcreate is a utility for creating LVM logical partitions inside the volume group specified. An example command is shown:

lvcreate -L10G -nhome vg

In this example we tell the volume, vg, that we want a new "partition" that is 10 GB, and named home. A device will be created in /dev/vg/home that you can treat exactly as you would a hard drive partition (i.e. /dev/hda1).