What is a holistic practitioner exactly?

Hard to be exact. This phrase has become a catch-all.It has come to have different meanings for different people. May mean that they use both natural and pharmaceutical therapies. It could mean that they only use natural therapies. It could mean that they evaluate both mind and body of patient. They maybe a doctor, or might not. Since there are so many variables, it is important to be an informed patient.
Treats the whole pt . Holistic implies that the complete individual is treated, not just the disease. That is, the stress, living situation, nutrition etc are taken into consideration when treating , say, the flu. This can be a good thing. Problem is it opens the door to many intuitively hoped-for but scientifically unproven theories such as ' energy imbalances or imaginary toxins., etc. Check http://NCCIH.nih.org.
Can vary widely. Because holistic encompasses the whole, it can include so many different types of practitioners. One example is looking at oral pathology to find the root cause of disease. Take a look at the book "am dead or do I just feel like it". I have a free e-book on my website, 8 holistic dental tips. Please feel free to download it. www.holisticdentistlasvegas.com.