QM is relatively straightforward. The concept is this: particles don't actually have a position or spin or charge or mass or velocity. Instead there are different probabilities that we will observe a spin/charge/mass/velocity at various positions. There are 'dense' areas of probability where there is high likelihood to observe the particle/property and there are 'light' areas of probability where there is low likelihood to observe the particle property. You can think of these 'dense' and 'light' regions as crests and troughs of a wave. And just like water waves can interfere with each other (a big crest and a big trough cancel out in water, etc), so to can probability waves. As a result, instead of interacting 'classically' as objects, the quantum observations we make interact as waves of probability that can interact with each other like waves, resulting in all kinds of complex interference.

If that makes sense?