. and … are how terminals navigate around file systems.
The command cd . means “change directory (cd) to here (.)”
cd .. means “change directory to here, but one level up: my parent directory.”
So following that model, winrar and maybe older versions of 7zip used folders called ‘.’ as navigational tools within the archive browser. If you double-clicked through them, you’d see where they go.
I don’t know how much of this you knew, but the point is it shouldn’t freak you out too see them.
You two are doing fantastic and I love you.