Holiday mode is similar to pausing all your trade advertisements on. When you turn holiday mode on, none of your trade advertisements are visible and none can be responded to.
When you turn holiday mode back off, on your active (non-paused) trades are visible and can be responded to.
Trades that you have paused are unaffected by turning holiday mode on and off.
How to turn holiday mode on:
2. Click the red Holiday Mode button:
Done: you have now activated Holiday Mode: