Something errored out, quit unexpectedly, was force quit, or something like that and the OS "saved" the unsaved data for you just in case it was something you wanted.
For me I'm like 99.9999% of the time not needing such salvaged data. More often than not it's some temporary or intermediate file I would never select to save manually anyway... So I always just delete those myself (after looking of course...).
Those files are related to MS offices auto updates, at least most are...everytime it checks these files wind up in the trash, even if there are no updates to download.
Some apps are not good at doing their own "housekeeping". Usually, after a restart, OS X will move those files to the Trash as part of doing its own tidying up.