A few years ago when I was trying to understand the new JavaScript world with React and all its toys (moving from my background of PHP and other 'old-school' server-side rendered solutions), I hit problems similar to this.
This particular example isn't too bad -- looking at that line, it would be clear to me that I'm missing 'npm', and the solution is obvious -- find out what npm is, and get it installed. But the things that really bit me were tons of examples of JavaScript, which included strange lines like 'import', and I had no idea how to get my website's JavaScript to understand what an import is or any of the other syntax. Nothing would work! I didn't realise there was a whole ecosystem around how to build your code so that it can make use of these things. Every guide assumed I had things going, and I just didn't understand that I needed this other infrastructure in place first before I could do anything.