Probation in criminal law is a period of supervision over an offender, ordered by the court instead of serving time in prison. In some jurisdictions, the term probation applies only to community sentences (alternatives to incarceration), such as suspended sentences.

https://en.wikipedia.org/wiki/Probation

Probation means you’re serving your sentence but you’re not in prison. … you have been released from prison on licence or on parole. … have regular meetings with an ‘offender manager’. https://www.gov.uk/guide-to-probation