The name is constructed from two parts:
ls: listusb: usb
It lists usb devices that your machine (/kernel) knows has been connected; they may not necessarily be usable.
E.g. I have some sound output device connected via USB to one machine. On most of my machines I've switched from pulseaudio to pipewire¹, and I figured I'd bring that machine closer to the others so there's less variance. Unfortunately the sound output device didn't want to work with pipewire. The problem manifested as no sound and pipewire not listing the device. lsusb helped me know that the machine at the very least recognized the device, but wasn't currently able to use it. (It did actually also show up as an error in dmesg -H, but reinstating pulseaudio let the device work again as normally. So now I just have to live with a situation where some machines use pipewire because ~bluetooth~ and others use pulseaudio because … usb?¹)
¹ There's a memory of ALSA vs OSS I didn't want to be reminded of
I also find that calling systemd "SystemD" is a tell that someone is unfamiliar with or has a conspiratorial relationship to it. It's named "systemd", all lowercase (but I'm likely to capitalize it on sentence starts like a normal word). Using an ungrammatical uppercase D at the end of the word, that isn't even something the creators claim is correct, is … a choice.
(And it's a choice that reminds me of e.g. how rabid anti-cyclists in Norwegian can't even spell "cyclist" correctly, but instead consistently use "bicycleist".)