The Hal archive server is a place on the web where you can send your results from HalSail when they are of historical interest only. People can see them on the archive server, but you cannot change them, nor can you retrieve them from the archive server back into HalSail.
If you want to keep a snapshot of what is in your HalSail account in a form that can be used to restore the account, you need to make a Hal file.
A common use of the archive server is to allow you to spring clean your data at the beginning of each season after archiving your results from the previous season. That lets you remove any boats that are no longer relevant and set up a new schedule of races.
The archive server is accessible from the Admin menu.