Btrfs is a partition type/filesystem. It is meant to solve two problems.
One, it is meant so you can combine partitions from multiple drives (similar to raid 0,1, or 10). Technically it is capable of raid 5, but lacks reliable performance.
Two, it also provides reverse incremental snapshotting capabilities. Good for backing up data.
I'm using it in combination with grub-btrfs so if an update fails, I can boot from a snapshot to fix it without a live cd or reinstall.
Gamescope is what runs on a steam deck in gaming mode. I have my gaming PC configured to use gamescope for HDR gaming.
Finally, the link I sent is technically a war game. It is more meant to teach you to keep things secure more than anything else. In short you will control one of their cloud hosted machines over ssh and they hid the password somewhere on it. In order to win, you need a few commands: cat, vim, cd, ls, and git. It introduces them as you go. Eventually, I think it escalated to using netcat, honestly I stumbled through that part, and the git part too.
I'm not sure if mastering the terminal is a goal of yours, but I use tools to make it significantly easier. Instead of bash, I use ZSH. Combine that with Oh-my-zsh for theming and plugins(I like zsh-autocomplete, zsh-autosuggestions, zsh-syntaxhighlighting, fast-syntaxhighlighting), and zoxide to replace cd.
When it comes to updating, it can be different per distribution. Mint uses apt, typically you will need:
sudo apt update # Gets the latest version number of each package
sudo apt upgrade # Install the latest version of each available update
Apt is the package manager of most device based installation.
Yum/Dnf are the primary package managers for fedora and Red hat distros.
There are a few others, but I've gotten off topic enough.
Regardless, it is good to see someone joining the community. If you need any help with anything feel free to reach out to us, you are not in this alone. And if ever you can't figure out a command, try running it with --help. Ex:
ls --help
cd --help
cat --help