When a judge sentences you to formal probation, you are required to report to a probation officer at regular intervals (typically, once a month). When probation is ordered, you are required to agree to the terms of probation which include, among other things, 1) obey all laws; and 2) report any new criminal charges. Failure to comply with either of these conditions can result in a violation of probation. If you violate probation, you will be arrested and detained while you wait for a "probation violation hearing". The judge is the one who decides whether a violation has, in fact, occurred. You are not entitled to a jury trial.
If the judge finds that you are in violation, he/she will sentence you to incarceration. The length of incarceration will depend on the amount of jail/prison time that was suspended at the time that probation was granted. The judge may order you to serve the entire time or just a fraction of that time.
The punishment for violating probation is separate and apart from the punishment you may receive from your new case that led to the violation. That means that, even if you beat your new case and avoid a conviction, you can still be found in violation of probation. Also, if you are found guilty in the new case, you may have to serve time for that crime in addition to the time served for violating probation.