This process refers to 'de-gassing' the wine..
Where your wine has been sat in the fermenter, bubbling away, it will retain a certain level of carbon dioxide, or CO2.
What they are basically doing is asking you to 'remove' the CO2 from your wine in order to make it 'flat' - very much like the wine you get from the shops.
Essentially if your out all day, it doesn't matter.
What matters is that prior to bottling the wine, you remove all CO2.
Some vigorously stir. Some shake. Some use a de-gassing tool which fits to a power tool and some do nothing and like fizzy wine !!!
Personally, i have bought a de-gassing 'wine whip'. This is an item that is roughly £10 delivered and fits to a drill. You sterilise it, fit it to your favourite Black N Decker and give your wine that 'what for' for 10mins. This removes all CO2 and allows you to leave the wine to one side to clear then ultimately bottle at your leisure.
WW