A bindover is an ancient power dating back to at least the fourteenth century. Until a few years ago, people could be bound over to 'keep the peace and to be of good behaviour' for a period of (say) one year, in the sum of (say) £100. These days the good behaviour bit has been dropped but the idea is the same. No money changes hands unless you breach the peace again, when you can forfeit the cash.
If someone is arrested for breach of the peace (which the police find useful when they can't think of any better reason to arrest someone) the only penalty is a bindover. A bindover is not a conviction and does not go onto your criminal record.
It can be a very handy disposal to knock people's heads together without involving the law in all its flatfooted majesty.
Until a few years ago the defendant had to consent to a bindover. If his dudgeon was high enough he might refuse consent, in which case he would receive a nifty 28 days in chokey. It usually took rather less than 28 days for attitudes to be adjusted and common sense to prevail.