Amateur radio operators are expected to learn some fundamentals of basic electronics, and one of the things we learn about is OHM'S LAW, which expresses the relationship between voltage, current, and resistance.
Voltage (E) refers to the amount of electromotive force (EMF) applied to a circuit, and can be compared to water pressure going through a pipe. The more voltage, (or pressure) the more electrons (or water) flowing. Voltage is measured in volts.
Resistance (R) is just what it sounds like. If you put a blob of hair or sponge into a water pipe, it'll block the flow. In the same way, resistors resist the flow of electrons, and limit the amount of current flowing through a circuit. Resistance is measured in ohms.
Here's a bunch of different resistors. See those color bands on them? Each color represents a different number, and in simplest terms, the numbers express the resistor's value.
So what does Ohm's Law tell us? That within a circuit, voltage equals current times resistance. E=IR.
So, there ya have it.