It means Pluto does not dominate the path it travels around the Sun. There are many other objects in that same region of space, especially in the Kuiper Belt, so Pluto shares its orbital neighborhood instead of sweeping it clean.

What “cleared its orbit” means

A planet is expected to have become the main gravitational object in its orbit, with little else of similar size left nearby except moons or objects under its control. Pluto does not meet that third criterion, which is why it is classified as a dwarf planet rather than a full planet.

Easy way to picture it

Think of it like a very busy road:

  • A full planet is like a car that has mostly cleared the lane around it.
  • Pluto is more like a car moving through traffic, with lots of other objects in the same zone.

Why Pluto is different

Pluto sits in a crowded region beyond Neptune, where many icy bodies orbit. Because of that, its path overlaps with other objects in a way that is unlike the eight major planets.

Tiny example

If a planet were a boss controlling its neighborhood, Pluto would be more like a resident living in a packed apartment building. It is still a real world, just not the dominant one in its orbital area.

TL;DR: “Pluto has not cleared its orbit” means Pluto shares its orbital region with many other objects, so it is not gravitationally dominant enough to count as a full planet under the modern definition.