Imagine a hose filled with water. When you connect the hose to a faucet and put more water in, the water in the hose is gonna shoot out, right?
The copper wire is the hose. The electrons are the water. The pressure of the water is voltage. The movement of water is the current.
Try it out yourself! https://www.cei.washington.edu/lesson-plans-resources/water-model-for-electricity/