This video explains it fairly well https://www.youtube.com/watch?v=h2QaObLRLi0 though it doesn't cover everything. The doctor in that video also has their own website: https://www.epiphanyhealth.org/

The Primary Care (the PC in DPC) part refers to normal day-to-day health needs typically offered by general practitioners. Things like regular checkups, cuts and scrapes, lab work, typical vaccinations, etc etc. You already think about PC healthcare as a 'service', but you pay your insurance company (with your employer watching in for some reason) to pay the doctor for you. That adds a lot of overhead, more than one might think.

So DPC is where you pay for primary care by subscribing Directly (that's the D) to the doctor by paying a regular, fixed-price subscription to them. Typically $50-$100/mo, the doctor mentioned above charges $75/mo. Receive care as frequently as needed, with no copays, by any means, with reasonable prices for more specialized services like x-rays ($25), and an affordable in-house pharmacy for generic medications. Their office negotiates direct rates for lab work and can get a 95% discount (!) in some cases according to the doctor in the video.

Now there are some caveats, as per usual.

The biggest is that this strategy is specifically for Primary Care, not hospitalizations and other specialized or emergency health services. For those perhaps health insurance can still provide value. But that's the original purpose of insurance in the first place: covering unexpected large expenses. And that's the key: Primary Care is neither an unexpected nor large expense -- it's regular maintenance, more like an oil change; are you paying your insurance company to pay your mechanic to perform oil changes on your car? Unlikely, and it sounds like a bureaucratic nightmare on the face. Yet somehow this is business as usual for healthcare in the US.