According to our current understanding of quantum physics, the Planck length represents the smallest possible meaningful scale in the universe. It is defined as approximately 1.6 x 10^-35 meters. However, it's important to note that the Planck length is not a literal "building block" of space or a fixed distance that objects move through.
In quantum physics, the behavior of particles and fields is described by wavefunctions, which can be thought of as probability distributions. These wavefunctions can exhibit "quantization," meaning they can only take on certain discrete values. However, this does not imply that physical objects move from one Planck length to another in a step-by-step manner.
The concept of motion at such tiny scales is not well understood and falls within the realm of quantum gravity, a theoretical framework that aims to unify quantum mechanics and general relativity. Quantum gravity theories, such as string theory or loop quantum gravity, propose that space itself might have a fundamentally discrete or "grainy" nature at the Planck scale.
However, these theories are still highly speculative and lack experimental confirmation. Therefore, we currently do not have a definitive answer to how objects would move or transition from one Planck length to another. The behavior of particles and spacetime at such extreme scales is an active area of research and remains a subject of ongoing investigation and theoretical speculation.