Your probation interview is a critical stage of the case against you. It can affect how you are sentenced even in cases where you are accepting a plea offer with a promised sentence. It is important that you are honest, up front, and treat the interviewing officer with respect.
Probation offices have very different policies from county to county. Some allow your attorney to be with you during the interview. In such places, it is important to talk to your attorney to determine if it is necessary for your attorney to attend the meeting with you.
A probation officer will likely cover many topics including:
Your educational, work, and criminal history.
Your life history.
The facts and circumstances of the offense you will be sentenced for; and
Any mental health or substance abuse history.
After meeting with you, the probation department will provide a report to the court along with an opinion about an appropriate sentence. If probation is part of your sentence, the probation department will likely include proposed terms and conditions of probation that you will be obligated to follow.