[vrighter]

don't imagine a ball spinning. Imagine a spinning top. It acts as a gyroscope. When a force is applied to it it tries to resist it, but it also causes precession. The equations for that precession can be used for electrons in a particular context. This is how we discovered that particles have angular momentum in the first place. Whatever we measure in that context, is what we call a particle's spin. It's all about the angular momentum and the precession caused by an external force.

tldr: nothing is spinning in a particle. what we refer to as spin refers to how angular momentum is affected by external forces, which happens to behave similarly to a spinning gyroscope. So we called that property "spin"