Also, unless you’re one of those people who legitimately doesn’t care if food tastes good or not, learn to cook. You don’t have to be good a cooking everything, but develop a repertoire of food that is healthy and you like to eat.
The age where you could depend on a wife to be a good cook for you are long past.
/sbin is like /bin, but for system administrative type commands. /usr holds all the other software that isn’t critical to get the system up and running.
A device file is a special file that’s like a pointer to a piece of actual hardware, like a serial port or a hard drive. /dev also has some non-hardware special files like /dev/zero. When you read from that one, you get an endless stream of zeros. Or /dev/null, that discards any data that’s written to it.