I like to use the plumbing analogy for this explanation. Think of a water faucet. When the water is not flowing, there is pressure in the pipe. This pressure is caused by a mass of water molecules being forced in the direction toward your faucet. Let's not worry about where the force comes from for now, just the fact that it is there. The faucet is waiting to be turned on and let the potential pressure out.

Voltage is like the pressure behind the pipe. In this case, charges (electrons) are responsible for this pressure, rather than water molecules. In electronics, we refer to this pressure as potential; voltage is synonymous with potential difference. Voltage, like the water pressure, creates a flow from high potential to low potential. The sink has no potential, or pressure.

Electrical current is the flow of charges. In electricity, current flows when a circuit loop is closed. That is, a loop connecting a power source (battery) and a load (lamp or heater) are connected (the switch is on). The more charges that flow through a given area at an instance of time, the more current there is. This is like a firehose having more water flow than a garden hose. Current could be discussed further, however, I only intend to explain enough to answer the voltage question.

When electrical current flows, charges flow from high potential to low potential. (At this point, people might begins discerning the difference between electron and conventional current. I am intentionally avoiding this for the ELI5.) The more voltage there is, the more pressure there is, hence, the more current will flow. If there is no voltage, there is no current.

Now, voltage/current is only useful if it does useful work. That is where the concept of loading comes in. You may have heard of a resistor. In the pipe analogy, a resistor is like a kink in the pipe (note, in this case it is not doing anything useful). When the pipe is kinked, it resists flow causing a buildup of pressure on the end that the water is flowing in to. On the other end, there is less pressure. Now there is a potential difference across the kink. When current passes through a resistive element, like a heater coil, the same effect happens. A potential difference forms across the coil. This is a potential drop.

If a 12V battery was placed across a heater coil (rated to handle a 12V battery) then the full 12V would drop across the coil. In this case, energy in the flowing charges is converted to heat to do useful work.

To summarise, a power source such as a battery provides voltage. This voltage is a pressure of charges which forces a current when a circuit is closed. The voltage potential, in turn, drops across a load to do useful work.

I hope this helps. Note, this example is a very simplified model of electricity. If you wish, I can elaborate further tomorrow after my last final exam in electrical engineering.