Rho measures the sensitivity of an option price to changes in interest rates. It is the expected change in premium for each 1% change in interest rate, typically the "risk-free" rate (US Treasury Bill). As interest rates increase, the value of calls increases (a positive Rho value) and puts decrease (a negative Rho value).
For short term options, Rho is not as important. However, LEAPs options are more sensitive to interest rate change effects.
MarketChameleon.com displays the Rho in the custom columns of the stock’s Option Chain page, the "Option Greeks" tab of the Covered Calls Screener and the "Option Greeks" tab of the Naked Puts Screener .
Consider a hypothetical stock that’s trading exactly at its strike price of $100. The $100 calls and the $100 puts are both be exactly ATM. You might see the calls trading at a price of $1.00, while the puts may trade at a price of $0.90. When interest rates are low, the difference between call and put premiums will be small. As interest rates increase, this difference will get larger.