In LVM, disks are organized in logical volumes which get automatically extended as needed. For example, if /home get filled, it can take some free space from another volume (for example, /usr) automatically. Also a logical volume can include several harddisks. It makes it easy to extend /home, for example, by simply adding a new HD.
While installing openSUSE, you have the choice between ‘partition based’ and ‘LVM based’. The default - using partitions - is suitable for most users. LVM is normally used on servers (often in combination with RAID). It works well on desktop machines, allthough it is seldom necessary. openSUSE setup makes it easier than other distros setups.