A surprising number of facts about subatomic world can be understood in terms of the wave nature of particles. The most essential fact about a wave as far as the world of particles is concerned is its unlocalized nature.

A wave can’t be said to be exactly at this point or exactly at that point, at best it is said to be in this region or in that region.

The relevance of this unlocalized nature in the sub microscopic world is simply that the position of a particle can never be known, even in principle to an accuracy much greater than the wavelength of the particle.