The kill command allows you to specify which type of kill signal you want to send. -9 sends signal 9 or SIGKILL, and we’re sending it to pid 1.
That would force kill systemd, which I just have to assume will send your computer to a crashing halt.
The echo command is writing “c” to a file at /proc/sysrq-trigger which I don’t really know how it works but this suggests you’ll “crash the system without first unmounting file systems or syncing disks attached to the system.”
I haven’t installed fuck so I’m not sure how that works