Here’s the best way I have to explain it. Take something everyone is familiar with, car refueling:

Your gas tank has a 20 gallon capacity (for easy numbers). That’s enough stored energy in that tank for you to drive for hundreds of miles from full to empty.

The gas pump / petrol station pumps gasoline at 10 gallons per minute. That’s the flow rate. It’s also 600 gallons per hour, but that’s not how we measure it.

So now let’s take this to electric vehicles : replace gallons per minute with kilowatts. the flow rate is kilowatts. That’s simply measuring the rate the energy is flowing from A to B, like gallons per minute. It’s a way to tell how fast the energy is being moved.

The storage unit is kilowatt hours. That’s how much energy is stored in a given “tank”/ battery. It’s not always flowing, it is just an amount of stored energy like you would have 20 gallons of gasoline. You in theory could measure the 20 gallon tank as miles of range at your typical driving style, or amount of energy if you were to floor it for a few hours straight at full throttle, but we don’t do that- gallons works fine.

So it’s a weird way to think about it for an electric vehicle, but the way battery storage is talked about is the number of hours of energy it has stored. Like if you were to refer to the tank of fuel as a “two 10-gallon / hour tank”. It’s a gas tank that holds enough energy (gallons) to draw 10 gallons per hour out of it, for 2 hours. Not intuitive at all, but that’s how it’s done. This is why miles of range or % is used instead. kWh is more useful for generally comparing batteries against each other like you would compare size of the gas tank