A Certificate of Good Conduct is a declaration confirming that your previous behaviour does not warrant any objection to your performance of a specific task or role. You can request the certificate from your municipality.
You will be issued with a Certificate of Good Conduct provided that you have not committed a criminal offence relevant to the particular role, such as one requiring you to work with confidential data, vulnerable people, money, or goods.
If you work as a volunteer temporarily, you may still need a Certificate of Good Conduct. Even if there is no statutory obligation to provide the certificate, an employer or organization – volunteer or otherwise – can still ask you to provide one to perform a certain role.