>>2216253i have no idea what os are you using hut I'd assume you're using windows? the text thing is called terminal, similar to what command prompt/powershell is on windows. they're displaying a program called neofetch, often used to show the info of your system and customization like what theme are you using, what linux distro you're using, your window manager/DE etc. you can also get it on windows.
you can modify your windows in a lot of ways, you can change your theme, icon packs, the taskbar, how some certain application looks and a lot more. here's a guide to get you up to speed into windows customization or as people usually call it, ricing
https://www.ricing.chloechantelle.com/however as you can see that even something as simple as changing your theme required some "hacks" because windows does not natively support it and there's always a chance that it'll break after a windows feature update. the scene for windows ricing is also relatively small (and some of them locked their stuff behind a paywall) so the amount of customization you can do is not that much compared to say, linux.
most of the desktop that's posted here are based on linux, it offers the level of customization that windows simply doesn't. you can change almost everything about it, don't like your current desktop environment? you can change it. you like your current DE but you hate the file manager or any apps that it comes bundled with? you can change it, even with apps from another DE. the scene for custom theme and icons are also pretty huge compared to windows and making your own is actually not that hard. for starters, if you really wanna go deep into it you can immediately jump to a distro like arch, but for a better out of the box experience I'd recommend distro like Pop! OS, endeavourOS or linux mint (anything but manjaro). and you can start figuring stuff out by yourself, there are tons of guide for linux ricing on the internet.
