This equation computes Power in an electric circuit given the potential across the circuit and the current running through the circuit.
In other words there is a direct relationship between power in Watts (W), current in Amperes (A), and potential in Volts (V).
This basic equation is important in innumerable design and analyses of electrical circuits. For instance, if you know the maximum amperage in a home circuit by checking the rating on the circuit breaker. And you know the common voltage of a household circuit is 110 volts and most devices you plug into you home outlets are designed to run on 110 Volts (in the US - I know, smug Americans who think there is no world outside the US -- chuckle). A device that requires a certain amount of power will work in your home where the circuit breaker will support up to 20 Amps if the maximum power it requires is: `P = V*A_"max" = 110 V * 20 A"max" = 2200 W_"max"`. The maximum power this example circuit can support is then 2,200 Watts.
Power is also directly related with other fundamental electrical measures such as electrical resistance: `P = V^2/Omega = A^2 * Omega`
Note also: `W = J/s = N*m = (kg * m^2) / s^3`