DMOZ is the directory of the Open Directory Project or ODP for short. It is the largest human edited web directory on the internet. Because it is human edited, huge and it has been around for a long time, ODP is a well respected resource for some of the most popular search engines such as AOL, Google and many others.
This benefits you because if DMOZ will accept your website into their directory, then it is like an endorsement of your website's quality. In other words, having your link listed in DMOZ gives you a lot of street cred which means that it is another important factor in contributing to improving your search engine ranking.