It's another name for a 3.5mm jack plug..
Think of the plug you have on a set of headphones but instead of three contacts (stereo) this one will only have two.
You say a cable? is it the same plug on both ends? if so then it's a simple mono 3.5mm jack to 3.5mm jack which comes in 0.5m all the way upto 50m lengths
here's a 1m length from ebay
http://www.ebay.co.uk/itm/1m-Mono-3-...-/261720000969
Maplins or other stores will also have them
