Here's the short version.

A normal battery is a sealed cell. It has a positive and negative electrode, with an electrolyte between them. Usually many layers of this. When you charge it, a chemical change happens. When you discharge it, that chemical change is undone.

A redox flow battery uses fixed electrodes, but a liquid electrolyte that can be pumped and stored. This means you can increase overall storage capacity simply by adding more electrolyte tanks, without needing more electrodes. Think of it like a generator with a bigger gas tank.

The whole vanadium thing is just one of the metals used in the battery. There's a few kind of redox flow batteries using different chemistries

Yeah wikipedia is hit or miss, especially as technical people like to show off their fancy words and explain things in ways only technical people understand.

But it's Vanadium, and you can look that up elsewhere. The first large industrial vanadium battery (if I recall,) was some years back, I think in WA State.

source: wikipedia (link above)

As per usual Wikipedia sucks at explaining concepts that you don’t actually already understand.

but it's true, i have encountered exactly this phenomenon many times :/