Skyrim Special Edition save filenames clearly have useful information in them in a specific format. This information can be handy e.g. when going back through the save game history to decide which saves to keep and which to dump, since a directory full of multi-megabyte saved games can get very large.
Here are some example filenames:
What do the various components mean?
Feel free to update the community answer if you have only a little extra information to add.