Resistance is an important part of the electrical equation. A smaller hole in the nozzle of a water hose increases resistance. In pipes, friction on the walls makes resistance. In wires there is resistance from the wire itself and, if you add a light bulb with a fine tungsten filament, even more resistance is produced. You might think of the light bulb as the nozzle.
Water flow is measured in gallons per minute.
Electrical current flow is measured by the Ampere or Amp. This brings in something called Ohm's Law. Let's say you have turned the spigot on only half way, producing some resistance, with a hose attached to fill a pot with water. As you fill the pot with a constant pressure from the spigot you have constant flow rate through the hose. If you open the spigot all the way and double the pressure you are also doubling the flow rate.