Seeding rules are a set of rules that determine a torrent's Seeding Rank, a measure of how much it needs to be seeded. You can control seeding rules from UG_Options > Queue > Seeding. For the most part, the options are self-explanatory.
These rules determine how the seeding rank is calculated, and affect which torrent will be seeded first.
These rules control the assignment of the first priority status. First priority torrents override downloading torrent and normal seeding torrents in the queue.
These rules control when the seeding of a torrent stops.
Read the Azureus FAQ