Unfortunately, these type of questions are commonly addressed to attorneys and we are sincerely unable to provide any estimate of approximate jail time without more information. Your friend's charges related to sales of narcotics varies based on the type of drug that was possessed for sale, as well as the quantity. Also, having picked up new offenses while on bail would trigger a bail enhancement, clearly, new charges and will send a message to the Court that your friend is a danger to the community. You mentioned your friend is facing a violation of probation. Unless your friend is on active probation for a prior offense in which they pled guilty, the new charge will not trigger a probation violation. However, if they are on probation, they could be sent to state prison merely on the probation violation if they were previously convicted of a felony.
Your friend most definitely needs a competent attorney that can assist her with her multiple charges and/or cases.
It's impossible to predict the time she'd be looking at based on the facts presented. As you've described it, it definitely doesn't look good. She needs a good attorney on her side to evaluate any defenses/motions she may have and hopefully keep her out of prison.
She can be looking at a significant amount of time is all that can be said without knowing more about her situation. Three cases, one of which while she was out on bail, two of which while she was on probation...not good. Another message that being sent is that your friend has a serious substance abuse problem. The judge will want to try to address it - if it has not already been addressed - but if she will not take steps to get help and quit, at some point, punishment is the only remaining option.