The ARD program in Pennsylvania is the Accelerated Rehabilitative Diversion program. It's a program for first-time offenders to avoid a criminal conviction. A first-time offender could be a college student, a professional, a working person, it could be anybody who's never been in trouble before. There's going to be certain limited instances where a district attorney's office would consider someone whose criminal history goes far enough back where they could be considered a first-time offender at this point in time, but generally, it's a person who's never been in trouble before, who's never been convicted of a prior criminal offense in Pennsylvania or anywhere for that matter.
The ARD program would be a way for a person to, through other steps that would be taken, that it would satisfy the district attorney's office and the court as an alternative way to resolve the case rather than, say, proceeding to trial and potentially being found guilty or pleading guilty. It's a program that allows a person to avoid a criminal conviction if successfully completed.
Having an experienced Pennsylvania criminal defense attorney will help you best understand and navigate the ARD process. They should be involved from as early as possible in the case because even more is at stake for a first-time offender.