Notice Filed, OF UNAVAILABILITY FOR TRIAL...what does that mean?

You need to post more facts, but generally a notice of unavailability means that the attorney or party is not available do to a scheduling conflict with another case or Court, is on vacation, or has some other event (a surgery, a death in the family, etc.) that has made him or her unavailable

This a common but meaningless paper that lawyers file and serve in the hopes that the judge won't set a hearing or trial during the lawyer's vacation or other unavailable dates. But there's no code or rule of court that sets out this process, and nobody needs to actually avoid those dates. The lawyers can attack any opposing lawyer or party that sets something during that time as refusing to extend common courtesies, but the other party can just point out that the lawyer sending out the notice of unavailability had no authority to do so.