The GGP comment is sort of all over the place, but I will try my best (there will be a few simplifications.)
Electric charge of anything is both absolute and relative, but we mostly discuss it in a relative sense. In this case, you could apply (say) 600 mV potential across a 3mm wound, with (say) one electrode on the left and one on the right. Let's say you have a battery taped to your arm with wires leading to the wound (DO NOT try this at home! Playing around with electricity and open wounds is generally insane and could be deadly in nonintuitive ways!) - the relative potential of your body, relative to the surroundings, does not change. The left _of the wound_ is at +600 mV relative to the right, and the right -600 mV to the left, but your body's overall potential relative to your surroundings is unchanged, because again, everything is relative.
In the sense of absolute electric charge (of the body and the wound) essentially nothing changes. The electric current of the wound stimulation is a _flow_ of electrons, but there is no net movement.
"Grounding" (see "energy medicine", "earthing" etc) is mostly based around the sales of overpriced "healing" products that plug into the wall. Like many conspiracies there is a kernel of truth there - there _is_ actually a real, measurable difference (in potential, current flow, and how electric fields behave in your body, among other things) when you are electrically grounded vs. insulated from the ground - but the mechanisms and effects are a bit complex to explain in a comment. For more on the subject you might want to read on capacitive coupling.
Not his old posts, but if you're at all interested in seeing his old streams circa 2015/2016, there's an ongoing live stream here: https://www.youtube.com/watch?v=1iyknwjYbRE
