Most often, when your child is charged with a criminal offence, he or she will be released from the police station with a piece of paper titled Undertaking to a Peace Officer. The title of this piece of paper does not accurately communicate how important it is. It really should be called "Bail Conditions that Must be Followed", because that's really what it is.
When your child is charged and released from the police station with an Undertaking to a Peace Officer, in effect he or she has been released on a form of bail. Consequently, the rules that are listed on that piece of paper are very important. If your child breaks one of those rules, they can (and you should assume that they will) be charged with an additional criminal offence, for their failure to comply with the undertaking. The consequences of this additional charge can at times be as serious as the original charge they were facing.
A common example of a rule found on an Undertaking is a "no contact" rule. Often a young person is charged with a criminal offence that involved one or more of their friends as well, and as such, one of the rules on the Undertaking will be that they not have any contact with the friend they were with when they got into trouble in the first place. While it is difficult to expect a teenager to stop having contact with a close friend, it is important that they understand that for the time being, they absolutely must cease all contact with that person (both in person and over phone/internet), to ensure compliance with the condition. Breach charges for contact are one of the most common breach charges laid in relation to young persons, and they can often make pulling your child out of the criminal system more complicated than it would have otherwise been.
All that to say, that it is absolutely crucial that you sit down with your child and review the conditions of their Undertaking with them to ensure that they understand the importance of following these rules. Followings the rules can make all the difference in achieving a successful outcome in your child's case.