Hi! sorry about the jargon but racking is drawing off the wine from one vessel to another without taking the lees (more jargon) dead yeast cells and sediment along with the wine. If the wine is left on the sediment than it can get a mousey flavour, not that I have ever sucked a mouse, sort of an off/musty smell and taste. You can drink it when it has stopped bubbling ( it does need an airlock to stop it absorbing airbourne bad bacteria) and is nice and clear. It will benefit from being left longer however. Any more questions just post