What does a watt/volt measure and what other unit is it equivalent to?

To answer this question you have to understand the relationship between Power, Voltage and Current.
P=IV where P is power (measured in watts), I is current (measured in amperes) and V is voltage (measured in volts).
P/V = I therefore a watt/volt is a measure of current (i.e. the flow of electric charge) and would be equivalent to an ampere or 1 A