Breach gives -25% speed.
The breach description was unfortunately removed when multiple ships started inflicting it, in order to treat or consistently with other status effects.
The real problem is there is no good manual/summary of them anywhere. But it's not that different from having to read descriptions on other debuffs in game.
I think the confusion here is because HT has a unique which gives additional effects to Breached enemies, and since it introduced Breach and is still the most commonly used ship that employs it, that effect can easily be confused with the debuff description.
