The physics we're all familiar with is called Newtonian Physics, which is also called classical physics. It describes the motion of large things from ping-pong balls, to planets, stars, and even galaxies. You can know exactly where something is, how fast it's going, and where it will be in the future.
Just as light sometimes acts like a wave and sometimes acts like a particle, solid matter also can act like both a solid and a wave. It's just the effect is too small to notice unless you're working on an atomic scale.
The physics that describe very tiny things is called Quantum Mechanics. It describes the motion and properties of very tiny things like atoms and light photons. In quantum mechanics, the impossible happens all the time. A particle can literally be in two places at once. It can teleport through a barrier it shouldn't be able to go through. (That's called quantum tunneling.) That's just the tip of the ice burg. Quantum mechanics is governed by probability, but nothing is known for certain. The more accurately you know a particle's speed, the less you know about its location, and vice-versa.
So we have a set of rules for very tiny things, like atoms, and we have a set of rules for big things, like apples, people, and planets that are completely different. Scientists don't know how apples can have a different kind of physics than the atoms its made of. Answering that question is the modern day Holy Grail for scientists.