The vacuum of space is a force of nature that exerts a massive pull on everything within it. Zero gravity is the result. Since you can easily move anything there, no matter how big the mass, the propulsion force of a thruster is not necessary to move a spaceship. Small stabilizers at various points on a ship that emit impulses that affect the vacuum, and it works. These devices create a kind of counter-suction to the vacuum and thereby achieve a repulsion whose strength can be regulated. This makes it possible to navigate precisely in a vacuum without having to install thrusters everywhere.
This technology is also an integral part of any military armor, enabling operations on planets without atmosphere, with different gravity, or in space itself.