Have you ever needed to create an empty folder structure with many levels of repetitively-named folders? This doesn't happen a lot, obviously, but if you try using Finder for this task, you'll quickly discover it's really tedious. But a quick trip to Terminal makes the task very fast, and it's not overly complicated.
Let's say you need a folder structure to handle reports that you'll be receiving weekly, but need to keep track of over both quarters and years. One way to handle that would be with a folder structure like this:
(Hopefully obviously, the same structure repeats within each separate year's folder.) Creating that many multi-leveled folders in Finder would be time consuming and tedious. But in Terminal, you can create the entire structure with just one command:
mkdir -p 202{0..5}/qtr{1..4}/week{1..13}
That command takes under a second on my iMac to create the entire directory structure (over 330 folders). Zoom! So how does this work?