Propulsion in space requires the ejection of mass for an equal force in the opposite direction. Or you can capture moving mass and use that momentum.
There was even some speculation of dropping nuclear weapons out the tail and using a shield to let it push the ship.
“Turning a screw outside a ship”
And the above statement refers to ????
Nuclear reactor’s create heat - for transportation it’s all a matter of converting that heat energy into some form of thrust.
In an airplane a “combustion engine” (which uses heat created by the burning of a fuel) drives a turbine. Nuclear powered naval craft use the heat’s reactor to turn water into steam to drive a turbine and the turbine driving “the screw”.
But, it’s all a matter of what you do with the energy from the reactor.
A nuclear powered space vehicle might use a “nuclear electric system”, where nuclear reactors are a heat source for electric ion drives, to expel plasma out of nozzles to propel & maneuver spacecraft already in space.
Apparently NASA thinks so too and has R&D programs in the hopper, with Boeing and others, to investigate the idea.