Accuracy is a combat stat that defines how much of a salvo, if any, actually hits its target.

There are two tiers of accuracy, full hit accuracy, partial hit accuracy.
Full hit accuracy depends on target size and the relative Combat Speed between shooter and target.

Partial hit accuracy depends on shooter shots per second and gun count.

Envision combat as a series of salvos shot by one ship against another ship.
All guns of a particular ship fire at once and have the same rate of fire.
Lets say you have 16 guns, the guns create a target grid of 4x4 to maximize the chance something hits. Still, they try to aim in such a way that the entire grid matches the target size so they can in fact hit all shots if they are lucky.
Lets say your guns have a rate of fire of 8 rounds per second. That means you shoot 8 grids of 4x4 at your target. The target has to dodge all 8 of those fired grids. So as you can imagine there is a good chance they won't dodge all 8.