In a nutshell, an end play is simply arranging for the opponents to lead a suit which will be to your advantage. Arranging an endplay involves listening carefully to the bidding, deducing the defenders' hand-shapes, and removing “safe” leads from their hands until the only lead they can make gives you the extra trick. As he points out, it may not always work but it gives the defenders a chance to go wrong.
The converse of this is dealt with in the second half. If (as defender) you recognise what declarer is trying to do, you may have a chance to stop it.
This does de-mystify the subject and will make a good addition to the armoury of ambitious players.