That’s a log file.
What it means: there’s something in my laptop, that’s regularly taking screenshots of both my desktop, and login screen.
See the last entry, Saturday at midnight? Wasn’t even home, laptop had been closed for hours. Figure that one out.
Considering how careful I am, well, good to know I attract the best. I guess.
I can pretty much guarantee you will never again see a log like this.
If you want to see what’s happening inside your Mac, go > Applications > Utilities > Console
Logs for everything are found there.