The ESR parameter of the input panel sets the Equivalent Series Resistance of the specific type of capacitors. Enter the value in mili-ohms (1E-3 ohm). Each capacitor type is described by the 3 parameters CAP, ESR and ESL in the same row.
The circuit simulated will have NUM capacitors of this type in parallel.
Typical ESR values can be found in this table:
The table is missing at: http://www.pdntool.com/faq/esr