Rho is the option's price change per one-percentage-point change in the risk-free rate. It is negligible for short-dated options and material for long-dated ones, where rate exposure compounds over years.
Calls gain from higher rates and puts lose, because the strike's present value falls as rates rise. For a 30-day spread the effect is noise; for a two-year LEAPS a full point of rate change moves the price meaningfully. This is why careful pricing engines fetch a Treasury yield curve and price each expiration with its own matching rate instead of one constant.