Window managers in Linux take direct command from the display server (Xorg, Wayland, etc.) to decide where to position windows and what they should look like. Whereas “window managers” on MacOS/Windows are tricking the original window manager provided by the OS into positioning windows a certain way. I’m simplifying here, but hope that clears things up.

I’m pretty sure it doesn’t, what sound does it represent?

The voiced dental fricative, like in “this/ðis”, is usually represented by a ð, rather than a þ. Which is usually used for a voiceless dental fricative, like in “thin/þin”. Had to learn ðis as a foreigner living in Iceland, as Icelandic still uses boþ characters.