Inductance is a measurement of the potential magnetic capacity of a loop of wire measured in Henries (electrical symbol H).  Inductance is a measure of capacity in the same sense that a 1 liter container can hold that much liquid.  An inductance of 1 Henry means that the loop is capable of storing one amp at 1 volt for 1 second.

An inductor (antenna) attached to a capacitor forms an electrical circuit that will resonate (oscillate) when a signal is injected.  The inductance is measured with a meter to calculate the amount of capacitance needed to resonate at the 134.2 kHz.

This formula shows the relationship of inductance (in microHenries) to the capacitance (in nanoFarads) for the antenna to resonate at 134.2 kHz.