Present count is a type of standard
count signal. A defender's
second discard in a suit shows count:
- A high card shows an even number of remaining cards in the suit.
- A low card shows an odd number of remaining cards in the suit.
Examples
♣ A 8 5 4 3
Say you must make a discard at some point, and wish to encourage a club lead from partner. Playing standard attitude signals, your first discard would be a high club, i.e. the ♣ 8.
If you get a second chance to discard in the suit (and can afford to do so), then you can show "present count". Left with 
A543, you have an even number of clubs and would therefore discard the ♣ 5 at your second discarding opportunity.
♦ A K 8 4 3 2
In this case, the 
8 would be your first discard (encouraging). But your second discard would be the ♦ 2 to show an odd number of remaining diamonds.
♠ 8 4 3 2
This time, imagine that you want to discourage a spade lead. Your first discard would be the ♠ 2. Hence with three spades left, your second discard would be the ♠ 3 to give present count.
