I think by "build something" that involves looking up precise stuff as one goes along.

I learned Go without looking at any tutorials. I just started coding and googled for things like "array declaration in Golang" as I needed it. My first Go program was a dynamic image resizer that used seam carving to intelligently scale images. I had never used Go before, nor implemented that particular algorithm before.

So by "build something", that is to say I didn't go through a book first, or a tutorial first, or a video first.