Current is the flow of charge and is measured in amperes (A). What pushes the charge round a circuit is the potential difference (p.d.) of the supply, measured in volts (V). The p.d. between two points is the energy transferred per unit charge that passes between them. One volt is one joule of energy transferred for each coulomb of charge, so if 12 J of energy is transferred to 4 C of charge, the p.d. is 12 ÷ 4 = 3 V.
Resistance is how much a component opposes the flow of current. It is measured in ohms (Ω). The current in a circuit depends on both the p.d. and the resistance. A larger p.d. gives a larger push, so the current increases. A larger resistance makes it harder for charge to flow, so the current decreases.
For a fixed resistor at constant temperature, doubling the p.d. doubles the current. To find out how a component behaves you can record the p.d. across it and the current through it for different settings, and then calculate its resistance.